Multi-objective Fonseca-Fleming example with the mNBI algorithm#

In this example, the modified Normal Boundary Intersection algorithm (mNBI) is used to solve the FonsecaFleming optimization problem [FF95]:

\[\begin{split}\begin{aligned} \text{minimize the objective function } & f_1(x) = 1 - exp(-\sum_{i=1}^{d}((x_i - 1 / sqrt(d)) ^ 2)) \\ & f_2(x) = 1 + exp(-\sum_{i=1}^{d}((x_i + 1 / sqrt(d)) ^ 2)) \\ \text{with respect to the design variables }&x\\ \text{subject to the bound constraint} & x\in[-4,4]^d \end{aligned}\end{split}\]

We also show how the Pareto front can be refined.

from __future__ import annotations

from gemseo import configure_logger
from gemseo import execute_algo
from gemseo import execute_post
from gemseo.algos.opt.mnbi.settings.mnbi_settings import MNBI_Settings
from gemseo.problems.multiobjective_optimization.fonseca_fleming import FonsecaFleming

configure_logger()
<RootLogger root (INFO)>

Solve the Fonseca-Fleming optimization problem#

The 3 sub-optimization problems of mNBI are solved with SLSQP, a gradient-based optimization algorithm from the NLOPT library, with a maximum of 100 iterations. The analytic gradients are provided.

opt_problem = FonsecaFleming()
mnbi_settings = MNBI_Settings(
    max_iter=1000,
    sub_optim_max_iter=100,
    n_sub_optim=3,
    sub_optim_algo="NLOPT_SLSQP",
)
result = execute_algo(opt_problem, settings_model=mnbi_settings)
INFO - 02:29:38: Optimization problem:
INFO - 02:29:38:    minimize FonsecaFleming
INFO - 02:29:38:    with respect to x
INFO - 02:29:38:    over the design space:
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:       | Name | Lower bound | Value | Upper bound | Type  |
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:       | x[0] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | x[1] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | x[2] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38: Solving optimization problem with algorithm MNBI:
INFO - 02:29:38: Searching for the individual optimum of each objective
INFO - 02:29:38: Optimization problem:
INFO - 02:29:38:    minimize f_0
INFO - 02:29:38:    with respect to x
INFO - 02:29:38:    over the design space:
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:       | Name | Lower bound | Value | Upper bound | Type  |
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:       | x[0] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | x[1] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | x[2] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:      1%|          | 6/1000 [00:00<00:01, 592.61 it/sec, obj=[2.04753293e-04 9.82706845e-01]]
INFO - 02:29:38:      1%|          | 7/1000 [00:00<00:01, 608.79 it/sec, obj=[1.10060811e-06 9.81607360e-01]]
INFO - 02:29:38:      1%|          | 8/1000 [00:00<00:01, 624.64 it/sec, obj=[9.01501096e-14 9.81684376e-01]]
INFO - 02:29:38:      1%|          | 9/1000 [00:00<00:01, 639.55 it/sec, obj=[8.15628010e-10 9.81684362e-01]]
INFO - 02:29:38:      1%|          | 10/1000 [00:00<00:01, 693.12 it/sec, obj=[7.07334191e-12 9.81684374e-01]]
INFO - 02:29:38:      1%|          | 11/1000 [00:00<00:01, 690.49 it/sec, obj=[4.27435864e-14 9.81684376e-01]]
INFO - 02:29:38:      1%|          | 12/1000 [00:00<00:01, 646.36 it/sec, obj=[0.         0.98168436]]
INFO - 02:29:38:      1%|▏         | 13/1000 [00:00<00:01, 654.68 it/sec, obj=[0.         0.98168436]]
INFO - 02:29:38:      1%|▏         | 14/1000 [00:00<00:01, 692.66 it/sec, obj=[0.         0.98168436]]
INFO - 02:29:38: Optimization result:
INFO - 02:29:38:    Optimizer info:
INFO - 02:29:38:       Status: None
INFO - 02:29:38:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
INFO - 02:29:38:       Number of calls to the objective function by the optimizer: 17
INFO - 02:29:38:    Solution:
INFO - 02:29:38:       Objective: 0.0
INFO - 02:29:38:       Design space:
INFO - 02:29:38:          +------+-------------+--------------------+-------------+-------+
INFO - 02:29:38:          | Name | Lower bound |       Value        | Upper bound | Type  |
INFO - 02:29:38:          +------+-------------+--------------------+-------------+-------+
INFO - 02:29:38:          | x[0] |      -4     | 0.5773502684895009 |      4      | float |
INFO - 02:29:38:          | x[1] |      -4     | 0.5773502684994094 |      4      | float |
INFO - 02:29:38:          | x[2] |      -4     | 0.5773502684993135 |      4      | float |
INFO - 02:29:38:          +------+-------------+--------------------+-------------+-------+
INFO - 02:29:38: Optimization problem:
INFO - 02:29:38:    minimize f_1
INFO - 02:29:38:    with respect to x
INFO - 02:29:38:    over the design space:
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:       | Name | Lower bound | Value | Upper bound | Type  |
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:       | x[0] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | x[1] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | x[2] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:      2%|▏         | 15/1000 [00:00<00:01, 566.95 it/sec, obj=[1. 1.]]
INFO - 02:29:38:      2%|▏         | 16/1000 [00:00<00:01, 596.14 it/sec, obj=[0.99999998 0.9931056 ]]
INFO - 02:29:38:      2%|▏         | 17/1000 [00:00<00:01, 600.53 it/sec, obj=[0.99688636 0.14955784]]
INFO - 02:29:38:      2%|▏         | 18/1000 [00:00<00:01, 581.28 it/sec, obj=[0.9492493  0.07206897]]
INFO - 02:29:38:      2%|▏         | 19/1000 [00:00<00:01, 588.07 it/sec, obj=[9.82706845e-01 2.04753293e-04]]
INFO - 02:29:38:      2%|▏         | 20/1000 [00:00<00:01, 594.86 it/sec, obj=[9.81607360e-01 1.10060811e-06]]
INFO - 02:29:38:      2%|▏         | 21/1000 [00:00<00:01, 600.50 it/sec, obj=[9.81684376e-01 9.24815780e-14]]
INFO - 02:29:38:      2%|▏         | 22/1000 [00:00<00:01, 606.74 it/sec, obj=[9.81684362e-01 8.52572346e-10]]
INFO - 02:29:38:      2%|▏         | 23/1000 [00:00<00:01, 628.11 it/sec, obj=[9.81684374e-01 7.39219796e-12]]
INFO - 02:29:38:      2%|▏         | 24/1000 [00:00<00:01, 630.31 it/sec, obj=[9.81684376e-01 4.29656311e-14]]
INFO - 02:29:38:      2%|▎         | 25/1000 [00:00<00:01, 613.54 it/sec, obj=[0.98168436 0.        ]]
INFO - 02:29:38:      3%|▎         | 26/1000 [00:00<00:01, 618.91 it/sec, obj=[0.98168436 0.        ]]
INFO - 02:29:38:      3%|▎         | 27/1000 [00:00<00:01, 637.39 it/sec, obj=[0.98168436 0.        ]]
INFO - 02:29:38: Optimization result:
INFO - 02:29:38:    Optimizer info:
INFO - 02:29:38:       Status: None
INFO - 02:29:38:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
INFO - 02:29:38:       Number of calls to the objective function by the optimizer: 17
INFO - 02:29:38:    Solution:
INFO - 02:29:38:       Objective: 0.0
INFO - 02:29:38:       Design space:
INFO - 02:29:38:          +------+-------------+---------------------+-------------+-------+
INFO - 02:29:38:          | Name | Lower bound |        Value        | Upper bound | Type  |
INFO - 02:29:38:          +------+-------------+---------------------+-------------+-------+
INFO - 02:29:38:          | x[0] |      -4     | -0.5773502685200489 |      4      | float |
INFO - 02:29:38:          | x[1] |      -4     | -0.5773502685300462 |      4      | float |
INFO - 02:29:38:          | x[2] |      -4     | -0.5773502685281993 |      4      | float |
INFO - 02:29:38:          +------+-------------+---------------------+-------------+-------+
INFO - 02:29:38: Solving mNBI sub-problem for phi_beta = [0.49084218 0.49084218]
INFO - 02:29:38: Optimization problem:
INFO - 02:29:38:    minimize -t_extraction
INFO - 02:29:38:    with respect to t, x
INFO - 02:29:38:    subject to constraints:
INFO - 02:29:38:       beta_sub_optim_constraint <= 0.0
INFO - 02:29:38:    over the design space:
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:       | Name | Lower bound | Value | Upper bound | Type  |
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:       | x[0] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | x[1] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | x[2] |      -4     |   0   |      4      | float |
INFO - 02:29:38:       | t    |     -inf    |   0   |     inf     | float |
INFO - 02:29:38:       +------+-------------+-------+-------------+-------+
INFO - 02:29:38:      3%|▎         | 28/1000 [00:00<00:01, 545.98 it/sec, obj=[0.63212056 0.63212056]]
INFO - 02:29:38: Optimization result:
INFO - 02:29:38:    Optimizer info:
INFO - 02:29:38:       Status: None
INFO - 02:29:38:       Message: Successive iterates of the design variables are closer than xtol_rel or xtol_abs. GEMSEO stopped the driver.
INFO - 02:29:38:       Number of calls to the objective function by the optimizer: 4
INFO - 02:29:38:    Solution:
INFO - 02:29:38:       The solution is feasible.
INFO - 02:29:38:       Objective: 0.14391425994444806
INFO - 02:29:38:       Standardized constraints:
INFO - 02:29:38:          beta_sub_optim_constraint = [ 8.16013923e-15 -4.96824804e-15]
INFO - 02:29:38:       Design space:
INFO - 02:29:38:          +------+-------------+------------------------+-------------+-------+
INFO - 02:29:38:          | Name | Lower bound |         Value          | Upper bound | Type  |
INFO - 02:29:38:          +------+-------------+------------------------+-------------+-------+
INFO - 02:29:38:          | x[0] |      -4     | -9.676703882632864e-13 |      4      | float |
INFO - 02:29:38:          | x[1] |      -4     | -9.676703882632864e-13 |      4      | float |
INFO - 02:29:38:          | x[2] |      -4     | -9.676703882632864e-13 |      4      | float |
INFO - 02:29:38:          | t    |     -inf    |  -0.1439142599444481   |     inf     | float |
INFO - 02:29:38:          +------+-------------+------------------------+-------------+-------+
INFO - 02:29:38:      3%|▎         | 29/1000 [00:00<00:02, 387.04 it/sec, obj=[0.63212056 0.63212056]]
INFO - 02:29:38: Optimization result:
INFO - 02:29:38:    Optimizer info:
INFO - 02:29:38:       Status: None
INFO - 02:29:38:       Message: None
INFO - 02:29:38:       Number of calls to the objective function by the optimizer: 36
INFO - 02:29:38:    Solution:
INFO - 02:29:38:       Objective: 0.8939534673502061
INFO - 02:29:38:    Pareto efficient solutions:
INFO - 02:29:38:       Pareto optimal points : 9 / 29
INFO - 02:29:38:       Utopia point : [0. 0.]
INFO - 02:29:38:       Compromise solution (closest to utopia) : [[0.63212056 0.63212056]]
INFO - 02:29:38:       Distance from utopia : 0.8939534673502061
INFO - 02:29:38:       Objective values:
INFO - 02:29:38:          +------+----------+----------+----------+
INFO - 02:29:38:          | name |        1 |        2 |        3 |
INFO - 02:29:38:          +------+----------+----------+----------+
INFO - 02:29:38:          |    1 |        0 | 0.981684 | 0.632121 |
INFO - 02:29:38:          |    2 | 0.981684 |        0 | 0.632121 |
INFO - 02:29:38:          +------+----------+----------+----------+
INFO - 02:29:38:       Design space:
INFO - 02:29:38:          +-------+-------------+---------+----------+---+-------------+-------+
INFO - 02:29:38:          |  name | lower_bound |       1 |        2 | 3 | upper_bound |  type |
INFO - 02:29:38:          +-------+-------------+---------+----------+---+-------------+-------+
INFO - 02:29:38:          | x (1) |          -4 | 0.57735 | -0.57735 | 0 |           4 | float |
INFO - 02:29:38:          | x (2) |          -4 | 0.57735 | -0.57735 | 0 |           4 | float |
INFO - 02:29:38:          | x (3) |          -4 | 0.57735 | -0.57735 | 0 |           4 | float |
INFO - 02:29:38:          +-------+-------------+---------+----------+---+-------------+-------+

Display the Pareto front#

GEMSEO detects the Pareto optimal points and the dominated ones. The Fonseca-Fleming problem is interesting because its Pareto front is not convex. The mNBI algorithm successfully computes it.

execute_post(opt_problem, post_name="ParetoFront", save=False, show=True)
Pareto front
<gemseo.post.pareto_front.ParetoFront object at 0x7fb162d95070>

Solve the Fonseca-Fleming optimization problem more finely#

The Pareto front is then refined with 10 sub-optimizations instead of 3.

opt_problem = FonsecaFleming()
mnbi_settings.n_sub_optim = 10
result = execute_algo(opt_problem, settings_model=mnbi_settings)
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize FonsecaFleming
    INFO - 02:29:39:    with respect to x
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound | Value | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39: Solving optimization problem with algorithm MNBI:
    INFO - 02:29:39: Searching for the individual optimum of each objective
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize f_0
    INFO - 02:29:39:    with respect to x
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound | Value | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:      1%|          | 6/1000 [00:00<00:01, 634.40 it/sec, obj=[2.04753293e-04 9.82706845e-01]]
    INFO - 02:29:39:      1%|          | 7/1000 [00:00<00:01, 647.98 it/sec, obj=[1.10060811e-06 9.81607360e-01]]
    INFO - 02:29:39:      1%|          | 8/1000 [00:00<00:01, 661.51 it/sec, obj=[9.01501096e-14 9.81684376e-01]]
    INFO - 02:29:39:      1%|          | 9/1000 [00:00<00:01, 672.69 it/sec, obj=[8.15628010e-10 9.81684362e-01]]
    INFO - 02:29:39:      1%|          | 10/1000 [00:00<00:01, 726.01 it/sec, obj=[7.07334191e-12 9.81684374e-01]]
    INFO - 02:29:39:      1%|          | 11/1000 [00:00<00:01, 723.98 it/sec, obj=[4.27435864e-14 9.81684376e-01]]
    INFO - 02:29:39:      1%|          | 12/1000 [00:00<00:01, 671.31 it/sec, obj=[0.         0.98168436]]
    INFO - 02:29:39:      1%|▏         | 13/1000 [00:00<00:01, 676.74 it/sec, obj=[0.         0.98168436]]
    INFO - 02:29:39:      1%|▏         | 14/1000 [00:00<00:01, 715.66 it/sec, obj=[0.         0.98168436]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 17
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       Objective: 0.0
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |       Value        | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     | 0.5773502684895009 |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     | 0.5773502684994094 |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     | 0.5773502684993135 |      4      | float |
    INFO - 02:29:39:          +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize f_1
    INFO - 02:29:39:    with respect to x
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound | Value | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:      2%|▏         | 15/1000 [00:00<00:01, 577.45 it/sec, obj=[1. 1.]]
    INFO - 02:29:39:      2%|▏         | 16/1000 [00:00<00:01, 607.53 it/sec, obj=[0.99999998 0.9931056 ]]
    INFO - 02:29:39:      2%|▏         | 17/1000 [00:00<00:01, 612.95 it/sec, obj=[0.99688636 0.14955784]]
    INFO - 02:29:39:      2%|▏         | 18/1000 [00:00<00:01, 592.26 it/sec, obj=[0.9492493  0.07206897]]
    INFO - 02:29:39:      2%|▏         | 19/1000 [00:00<00:01, 599.32 it/sec, obj=[9.82706845e-01 2.04753293e-04]]
    INFO - 02:29:39:      2%|▏         | 20/1000 [00:00<00:01, 606.12 it/sec, obj=[9.81607360e-01 1.10060811e-06]]
    INFO - 02:29:39:      2%|▏         | 21/1000 [00:00<00:01, 611.05 it/sec, obj=[9.81684376e-01 9.24815780e-14]]
    INFO - 02:29:39:      2%|▏         | 22/1000 [00:00<00:01, 617.23 it/sec, obj=[9.81684362e-01 8.52572346e-10]]
    INFO - 02:29:39:      2%|▏         | 23/1000 [00:00<00:01, 638.88 it/sec, obj=[9.81684374e-01 7.39219796e-12]]
    INFO - 02:29:39:      2%|▏         | 24/1000 [00:00<00:01, 641.22 it/sec, obj=[9.81684376e-01 4.29656311e-14]]
    INFO - 02:29:39:      2%|▎         | 25/1000 [00:00<00:01, 623.87 it/sec, obj=[0.98168436 0.        ]]
    INFO - 02:29:39:      3%|▎         | 26/1000 [00:00<00:01, 628.75 it/sec, obj=[0.98168436 0.        ]]
    INFO - 02:29:39:      3%|▎         | 27/1000 [00:00<00:01, 647.00 it/sec, obj=[0.98168436 0.        ]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 17
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       Objective: 0.0
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |        Value        | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     | -0.5773502685200489 |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     | -0.5773502685300462 |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     | -0.5773502685281993 |      4      | float |
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39: Solving mNBI sub-problem for phi_beta = [0.87260832 0.10907604]
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize -t_extraction
    INFO - 02:29:39:    with respect to t, x
    INFO - 02:29:39:    subject to constraints:
    INFO - 02:29:39:       beta_sub_optim_constraint <= 0.0
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound | Value | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     |   0   |      4      | float |
    INFO - 02:29:39:       | t    |     -inf    |   0   |     inf     | float |
    INFO - 02:29:39:       +------+-------------+-------+-------------+-------+
    INFO - 02:29:39:      3%|▎         | 28/1000 [00:00<00:01, 556.86 it/sec, obj=[0.90043834 0.20664322]]
    INFO - 02:29:39:      3%|▎         | 29/1000 [00:00<00:01, 557.43 it/sec, obj=[0.91873293 0.15869784]]
    INFO - 02:29:39:      3%|▎         | 30/1000 [00:00<00:01, 557.02 it/sec, obj=[0.91966962 0.15614908]]
    INFO - 02:29:39:      3%|▎         | 31/1000 [00:00<00:01, 557.37 it/sec, obj=[0.91967277 0.15614049]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the design variables are closer than xtol_rel or xtol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 7
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       The solution is feasible.
    INFO - 02:29:39:       Objective: 0.047942550573600556
    INFO - 02:29:39:       Standardized constraints:
    INFO - 02:29:39:          beta_sub_optim_constraint = [ 6.93889390e-16 -1.83880688e-15]
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     |  -0.339464261305511  |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     | -0.3394642613042733  |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     | -0.3394642613061056  |      4      | float |
    INFO - 02:29:39:          | t    |     -inf    | -0.04794255057360056 |     inf     | float |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39: Solving mNBI sub-problem for phi_beta = [0.76353228 0.21815208]
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize -t_extraction
    INFO - 02:29:39:    with respect to t, x
    INFO - 02:29:39:    subject to constraints:
    INFO - 02:29:39:       beta_sub_optim_constraint <= 0.0
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     |  -0.339464261305511  |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     | -0.3394642613042733  |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     | -0.3394642613061056  |      4      | float |
    INFO - 02:29:39:       | t    |     -inf    | -0.04794255057360056 |     inf     | float |
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:      3%|▎         | 32/1000 [00:00<00:01, 506.66 it/sec, obj=[0.91967277 0.15614049]]
    INFO - 02:29:39:      3%|▎         | 33/1000 [00:00<00:01, 509.71 it/sec, obj=[0.84203912 0.33739501]]
    INFO - 02:29:39:      3%|▎         | 34/1000 [00:00<00:01, 512.35 it/sec, obj=[0.85527677 0.31046303]]
    INFO - 02:29:39:      4%|▎         | 35/1000 [00:00<00:01, 513.44 it/sec, obj=[0.85546004 0.31007996]]
    INFO - 02:29:39:      4%|▎         | 36/1000 [00:00<00:01, 514.48 it/sec, obj=[0.85546004 0.31007995]]
    INFO - 02:29:39:      4%|▎         | 37/1000 [00:00<00:01, 515.86 it/sec, obj=[0.85546009 0.31007984]]
    INFO - 02:29:39:      4%|▍         | 38/1000 [00:00<00:01, 516.49 it/sec, obj=[0.8554601  0.31007982]]
    INFO - 02:29:39:      4%|▍         | 39/1000 [00:00<00:01, 527.32 it/sec, obj=[0.8554601  0.31007983]]
    INFO - 02:29:39:      4%|▍         | 40/1000 [00:00<00:01, 529.48 it/sec, obj=[0.8554601  0.31007983]]
    INFO - 02:29:39:      4%|▍         | 41/1000 [00:00<00:01, 531.37 it/sec, obj=[0.85546009 0.31007984]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 12
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       The solution is feasible.
    INFO - 02:29:39:       Objective: 0.09364289795630283
    INFO - 02:29:39:       Standardized constraints:
    INFO - 02:29:39:          beta_sub_optim_constraint = [ 5.50654545e-08 -3.31157324e-08]
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     | -0.2256025551311831  |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     | -0.2256025557747829  |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     | -0.2256025548218257  |      4      | float |
    INFO - 02:29:39:          | t    |     -inf    | -0.09364289795630283 |     inf     | float |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39: Solving mNBI sub-problem for phi_beta = [0.65445624 0.32722812]
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize -t_extraction
    INFO - 02:29:39:    with respect to t, x
    INFO - 02:29:39:    subject to constraints:
    INFO - 02:29:39:       beta_sub_optim_constraint <= 0.0
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     | -0.2256025551311831  |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     | -0.2256025557747829  |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     | -0.2256025548218257  |      4      | float |
    INFO - 02:29:39:       | t    |     -inf    | -0.09364289795630283 |     inf     | float |
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:      4%|▍         | 42/1000 [00:00<00:01, 486.60 it/sec, obj=[0.77161691 0.45984452]]
    INFO - 02:29:39:      4%|▍         | 43/1000 [00:00<00:01, 488.08 it/sec, obj=[0.77767797 0.45048948]]
    INFO - 02:29:39:      4%|▍         | 44/1000 [00:00<00:01, 489.33 it/sec, obj=[0.77769345 0.45046534]]
    INFO - 02:29:39:      4%|▍         | 45/1000 [00:00<00:01, 489.06 it/sec, obj=[0.77769475 0.45046867]]
    INFO - 02:29:39:      5%|▍         | 46/1000 [00:00<00:01, 497.95 it/sec, obj=[0.77769346 0.45046536]]
    INFO - 02:29:39:      5%|▍         | 47/1000 [00:00<00:01, 499.73 it/sec, obj=[0.77769345 0.45046534]]
    INFO - 02:29:39:      5%|▍         | 48/1000 [00:00<00:01, 489.96 it/sec, obj=[0.77769345 0.45046533]]
   ERROR - 02:29:39: NLopt run failed: NLopt roundoff-limited, RoundoffLimited
Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/gemseo/envs/develop/lib/python3.9/site-packages/gemseo/algos/opt/nlopt/nlopt.py", line 384, in _run
    nlopt_problem.optimize(x_0.real)
  File "/home/docs/checkouts/readthedocs.org/user_builds/gemseo/envs/develop/lib/python3.9/site-packages/nlopt/nlopt.py", line 335, in optimize
    return _nlopt.opt_optimize(self, *args)
nlopt.RoundoffLimited: NLopt roundoff-limited
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 11
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       The solution is feasible.
    INFO - 02:29:39:       Objective: 0.1255363970177465
    INFO - 02:29:39:       Standardized constraints:
    INFO - 02:29:39:          beta_sub_optim_constraint = [1.38732549e-06 3.42942337e-06]
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |        Value        | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     | -0.1302316085444764 |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     | -0.1325189233805686 |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     | -0.1291321707661721 |      4      | float |
    INFO - 02:29:39:          | t    |     -inf    | -0.1255363970177465 |     inf     | float |
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39: Solving mNBI sub-problem for phi_beta = [0.5453802  0.43630416]
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize -t_extraction
    INFO - 02:29:39:    with respect to t, x
    INFO - 02:29:39:    subject to constraints:
    INFO - 02:29:39:       beta_sub_optim_constraint <= 0.0
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound |        Value        | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     | -0.1302316085444764 |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     | -0.1325189233805686 |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     | -0.1291321707661721 |      4      | float |
    INFO - 02:29:39:       | t    |     -inf    | -0.1255363970177465 |     inf     | float |
    INFO - 02:29:39:       +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:      5%|▍         | 49/1000 [00:00<00:02, 461.39 it/sec, obj=[0.77769345 0.45046533]]
    INFO - 02:29:39:      5%|▌         | 50/1000 [00:00<00:02, 463.80 it/sec, obj=[0.68555698 0.58426668]]
    INFO - 02:29:39:      5%|▌         | 51/1000 [00:00<00:02, 466.17 it/sec, obj=[0.68399938 0.57650637]]
    INFO - 02:29:39:      5%|▌         | 52/1000 [00:00<00:02, 468.46 it/sec, obj=[0.68462482 0.57558952]]
    INFO - 02:29:39:      5%|▌         | 53/1000 [00:00<00:02, 469.97 it/sec, obj=[0.68463858 0.57556374]]
    INFO - 02:29:39:      5%|▌         | 54/1000 [00:00<00:02, 470.33 it/sec, obj=[0.68463912 0.57556308]]
    INFO - 02:29:39:      6%|▌         | 55/1000 [00:00<00:02, 471.89 it/sec, obj=[0.68463912 0.57556308]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 10
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       The solution is feasible.
    INFO - 02:29:39:       Objective: 0.14185306201349607
    INFO - 02:29:39:       Standardized constraints:
    INFO - 02:29:39:          beta_sub_optim_constraint = [3.45183683e-06 4.64490810e-06]
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     | -0.04291047733084286 |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     | -0.04270203738455658 |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     | -0.04301066762956651 |      4      | float |
    INFO - 02:29:39:          | t    |     -inf    | -0.1418530620134961  |     inf     | float |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39: Solving mNBI sub-problem for phi_beta = [0.43630416 0.5453802 ]
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize -t_extraction
    INFO - 02:29:39:    with respect to t, x
    INFO - 02:29:39:    subject to constraints:
    INFO - 02:29:39:       beta_sub_optim_constraint <= 0.0
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     | -0.04291047733084286 |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     | -0.04270203738455658 |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     | -0.04301066762956651 |      4      | float |
    INFO - 02:29:39:       | t    |     -inf    | -0.1418530620134961  |     inf     | float |
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:      6%|▌         | 56/1000 [00:00<00:02, 447.14 it/sec, obj=[0.68463912 0.57556308]]
    INFO - 02:29:39:      6%|▌         | 57/1000 [00:00<00:02, 447.66 it/sec, obj=[0.57517744 0.68504627]]
    INFO - 02:29:39:      6%|▌         | 58/1000 [00:00<00:02, 448.96 it/sec, obj=[0.64468964 0.73529265]]
    INFO - 02:29:39:      6%|▌         | 59/1000 [00:00<00:02, 455.45 it/sec, obj=[0.57567735 0.68526336]]
    INFO - 02:29:39:      6%|▌         | 60/1000 [00:00<00:02, 450.73 it/sec, obj=[0.57562684 0.68458418]]
    INFO - 02:29:39:      6%|▌         | 61/1000 [00:00<00:02, 452.01 it/sec, obj=[0.57556309 0.68463912]]
    INFO - 02:29:39:      6%|▌         | 62/1000 [00:00<00:02, 453.56 it/sec, obj=[0.57556308 0.68463912]]
    INFO - 02:29:39:      6%|▋         | 63/1000 [00:00<00:02, 454.93 it/sec, obj=[0.57556308 0.68463912]]
    INFO - 02:29:39:      6%|▋         | 64/1000 [00:00<00:02, 456.46 it/sec, obj=[0.57556308 0.68463912]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 13
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       The solution is feasible.
    INFO - 02:29:39:       Objective: 0.141857085596892
    INFO - 02:29:39:       Standardized constraints:
    INFO - 02:29:39:          beta_sub_optim_constraint = [4.92134715e-08 3.53502475e-08]
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |        Value        | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     | 0.04285487868216808 |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     | 0.04297029133272012 |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     | 0.04279940357728407 |      4      | float |
    INFO - 02:29:39:          | t    |     -inf    |  -0.141857085596892 |     inf     | float |
    INFO - 02:29:39:          +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39: Solving mNBI sub-problem for phi_beta = [0.32722812 0.65445624]
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize -t_extraction
    INFO - 02:29:39:    with respect to t, x
    INFO - 02:29:39:    subject to constraints:
    INFO - 02:29:39:       beta_sub_optim_constraint <= 0.0
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound |        Value        | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     | 0.04285487868216808 |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     | 0.04297029133272012 |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     | 0.04279940357728407 |      4      | float |
    INFO - 02:29:39:       | t    |     -inf    |  -0.141857085596892 |     inf     | float |
    INFO - 02:29:39:       +------+-------------+---------------------+-------------+-------+
    INFO - 02:29:39:      6%|▋         | 65/1000 [00:00<00:02, 434.27 it/sec, obj=[0.57556308 0.68463912]]
    INFO - 02:29:39:      7%|▋         | 66/1000 [00:00<00:02, 435.68 it/sec, obj=[0.45296521 0.77610508]]
    INFO - 02:29:39:      7%|▋         | 67/1000 [00:00<00:02, 437.11 it/sec, obj=[0.4857272  0.79138788]]
    INFO - 02:29:39:      7%|▋         | 68/1000 [00:00<00:02, 442.50 it/sec, obj=[0.45359005 0.77673074]]
    INFO - 02:29:39:      7%|▋         | 69/1000 [00:00<00:02, 438.77 it/sec, obj=[0.45080811 0.77747394]]
    INFO - 02:29:39:      7%|▋         | 70/1000 [00:00<00:02, 440.00 it/sec, obj=[0.45046544 0.77769341]]
    INFO - 02:29:39:      7%|▋         | 71/1000 [00:00<00:02, 441.43 it/sec, obj=[0.45046534 0.77769345]]
    INFO - 02:29:39:      7%|▋         | 72/1000 [00:00<00:02, 442.59 it/sec, obj=[0.45046533 0.77769345]]
    INFO - 02:29:39:      7%|▋         | 73/1000 [00:00<00:02, 443.98 it/sec, obj=[0.45046533 0.77769345]]
    INFO - 02:29:39:      7%|▋         | 74/1000 [00:00<00:02, 445.18 it/sec, obj=[0.45046533 0.77769345]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 14
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       The solution is feasible.
    INFO - 02:29:39:       Objective: 0.12553645235059005
    INFO - 02:29:39:       Standardized constraints:
    INFO - 02:29:39:          beta_sub_optim_constraint = [ 1.49882953e-07 -4.26679669e-09]
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |       Value        | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     | 0.1305933450637484 |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     | 0.130790914197771  |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     | 0.1304983800119963 |      4      | float |
    INFO - 02:29:39:          | t    |     -inf    | -0.12553645235059  |     inf     | float |
    INFO - 02:29:39:          +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39: Solving mNBI sub-problem for phi_beta = [0.21815208 0.76353228]
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize -t_extraction
    INFO - 02:29:39:    with respect to t, x
    INFO - 02:29:39:    subject to constraints:
    INFO - 02:29:39:       beta_sub_optim_constraint <= 0.0
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound |       Value        | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     | 0.1305933450637484 |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     | 0.130790914197771  |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     | 0.1304983800119963 |      4      | float |
    INFO - 02:29:39:       | t    |     -inf    | -0.12553645235059  |     inf     | float |
    INFO - 02:29:39:       +------+-------------+--------------------+-------------+-------+
    INFO - 02:29:39:      8%|▊         | 75/1000 [00:00<00:02, 431.10 it/sec, obj=[0.45046533 0.77769345]]
    INFO - 02:29:39:      8%|▊         | 76/1000 [00:00<00:02, 432.42 it/sec, obj=[0.31703362 0.85215238]]
    INFO - 02:29:39:      8%|▊         | 77/1000 [00:00<00:02, 433.72 it/sec, obj=[0.40288985 0.87338417]]
    INFO - 02:29:39:      8%|▊         | 78/1000 [00:00<00:02, 438.35 it/sec, obj=[0.31715667 0.85249332]]
    INFO - 02:29:39:      8%|▊         | 79/1000 [00:00<00:02, 436.21 it/sec, obj=[0.31040011 0.85530776]]
    INFO - 02:29:39:      8%|▊         | 80/1000 [00:00<00:02, 437.16 it/sec, obj=[0.31008035 0.85545991]]
    INFO - 02:29:39:      8%|▊         | 81/1000 [00:00<00:02, 438.45 it/sec, obj=[0.3100799  0.85546007]]
    INFO - 02:29:39:      8%|▊         | 82/1000 [00:00<00:02, 439.58 it/sec, obj=[0.31007988 0.85546007]]
    INFO - 02:29:39:      8%|▊         | 83/1000 [00:00<00:02, 440.81 it/sec, obj=[0.31007988 0.85546008]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 13
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       The solution is feasible.
    INFO - 02:29:39:       Objective: 0.09364266739626721
    INFO - 02:29:39:       Standardized constraints:
    INFO - 02:29:39:          beta_sub_optim_constraint = [7.23490535e-07 8.72958074e-08]
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     |  0.2255448712436445  |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     |  0.2258763306714222  |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     |  0.2253855494856154  |      4      | float |
    INFO - 02:29:39:          | t    |     -inf    | -0.09364266739626721 |     inf     | float |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39: Solving mNBI sub-problem for phi_beta = [0.10907604 0.87260832]
    INFO - 02:29:39: Optimization problem:
    INFO - 02:29:39:    minimize -t_extraction
    INFO - 02:29:39:    with respect to t, x
    INFO - 02:29:39:    subject to constraints:
    INFO - 02:29:39:       beta_sub_optim_constraint <= 0.0
    INFO - 02:29:39:    over the design space:
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:       | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:       | x[0] |      -4     |  0.2255448712436445  |      4      | float |
    INFO - 02:29:39:       | x[1] |      -4     |  0.2258763306714222  |      4      | float |
    INFO - 02:29:39:       | x[2] |      -4     |  0.2253855494856154  |      4      | float |
    INFO - 02:29:39:       | t    |     -inf    | -0.09364266739626721 |     inf     | float |
    INFO - 02:29:39:       +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:      8%|▊         | 84/1000 [00:00<00:02, 428.79 it/sec, obj=[0.31007988 0.85546008]]
    INFO - 02:29:39:      8%|▊         | 85/1000 [00:00<00:02, 430.36 it/sec, obj=[0.17162737 0.91400636]]
    INFO - 02:29:39:      9%|▊         | 86/1000 [00:00<00:02, 432.19 it/sec, obj=[0.29857451 0.93068206]]
    INFO - 02:29:39:      9%|▊         | 87/1000 [00:00<00:02, 436.41 it/sec, obj=[0.17152252 0.91447953]]
    INFO - 02:29:39:      9%|▉         | 88/1000 [00:00<00:02, 434.23 it/sec, obj=[0.15696325 0.91937307]]
    INFO - 02:29:39:      9%|▉         | 89/1000 [00:00<00:02, 435.34 it/sec, obj=[0.15614412 0.91967146]]
    INFO - 02:29:39:      9%|▉         | 90/1000 [00:00<00:02, 435.83 it/sec, obj=[0.15614051 0.91967277]]
    INFO - 02:29:39:      9%|▉         | 91/1000 [00:00<00:02, 436.93 it/sec, obj=[0.15614049 0.91967277]]
    INFO - 02:29:39:      9%|▉         | 92/1000 [00:00<00:02, 437.83 it/sec, obj=[0.15614049 0.91967277]]
    INFO - 02:29:39:      9%|▉         | 93/1000 [00:00<00:02, 438.91 it/sec, obj=[0.15614049 0.91967277]]
    INFO - 02:29:39:      9%|▉         | 94/1000 [00:00<00:02, 439.87 it/sec, obj=[0.15614049 0.91967277]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: Successive iterates of the objective function are closer than ftol_rel or ftol_abs. GEMSEO stopped the driver.
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 15
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       The solution is feasible.
    INFO - 02:29:39:       Objective: 0.047941264984527124
    INFO - 02:29:39:       Standardized constraints:
    INFO - 02:29:39:          beta_sub_optim_constraint = [ 4.88540472e-06 -4.82444740e-08]
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | Name | Lower bound |        Value         | Upper bound | Type  |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:          | x[0] |      -4     |  0.3394255200896286  |      4      | float |
    INFO - 02:29:39:          | x[1] |      -4     |  0.3396321336864006  |      4      | float |
    INFO - 02:29:39:          | x[2] |      -4     |  0.3393262076587185  |      4      | float |
    INFO - 02:29:39:          | t    |     -inf    | -0.04794126498452712 |     inf     | float |
    INFO - 02:29:39:          +------+-------------+----------------------+-------------+-------+
    INFO - 02:29:39:     10%|▉         | 95/1000 [00:00<00:02, 395.38 it/sec, obj=[0.15614049 0.91967277]]
    INFO - 02:29:39: Optimization result:
    INFO - 02:29:39:    Optimizer info:
    INFO - 02:29:39:       Status: None
    INFO - 02:29:39:       Message: None
    INFO - 02:29:39:       Number of calls to the objective function by the optimizer: 123
    INFO - 02:29:39:    Solution:
    INFO - 02:29:39:       Objective: 0.8939534673502061
    INFO - 02:29:39:    Pareto efficient solutions:
    INFO - 02:29:39:       Pareto optimal points : 61 / 95
    INFO - 02:29:39:       Utopia point : [0. 0.]
    INFO - 02:29:39:       Compromise solution (closest to utopia) : [[0.63212056 0.63212056]]
    INFO - 02:29:39:       Distance from utopia : 0.8939534673502061
    INFO - 02:29:39:       Objective values:
    INFO - 02:29:39:          +------+----------+----------+----------+
    INFO - 02:29:39:          | name |        1 |        2 |        3 |
    INFO - 02:29:39:          +------+----------+----------+----------+
    INFO - 02:29:39:          |    1 |        0 | 0.981684 | 0.632121 |
    INFO - 02:29:39:          |    2 | 0.981684 |        0 | 0.632121 |
    INFO - 02:29:39:          +------+----------+----------+----------+
    INFO - 02:29:39:       Design space:
    INFO - 02:29:39:          +-------+-------------+---------+----------+---+-------------+-------+
    INFO - 02:29:39:          |  name | lower_bound |       1 |        2 | 3 | upper_bound |  type |
    INFO - 02:29:39:          +-------+-------------+---------+----------+---+-------------+-------+
    INFO - 02:29:39:          | x (1) |          -4 | 0.57735 | -0.57735 | 0 |           4 | float |
    INFO - 02:29:39:          | x (2) |          -4 | 0.57735 | -0.57735 | 0 |           4 | float |
    INFO - 02:29:39:          | x (3) |          -4 | 0.57735 | -0.57735 | 0 |           4 | float |
    INFO - 02:29:39:          +-------+-------------+---------+----------+---+-------------+-------+

Display the Pareto front#

We can clearly see the effect of the refinement.

execute_post(opt_problem, post_name="ParetoFront", save=False, show=True)
Pareto front
<gemseo.post.pareto_front.ParetoFront object at 0x7fb162b9cee0>

Total running time of the script: (0 minutes 0.873 seconds)

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