optimizeWithPlots

Optimize custom evaluation function and plot population density and convergence

Since R2025a

Syntax

opt = optimizeWithPlots(obj,iterations)

Description

opt = optimizeWithPlots(obj,iterations) optimizes the custom evaluation function specified in the optimizer object obj using the number of iterations in iterations and plots the population density and convergence.

Examples

Optimize Dipole Antenna for Directivity

Create a dipole antenna resonating at 75 MHz and calculate its maximum directivity.

Choose its length and width as design variables. Provide lower and upper bounds of length and width.

referenceAnt = design(dipole,75e6);
InitialDirectivity = max(max(pattern(referenceAnt,75e6)))

InitialDirectivity = 
2.1002

Bounds = [3 0.11; 7 0.13];

Use the SADEA optimizer to optimize this dipole antenna for its directivity. Specify an evaluation function for optimization using the CustomEvaluationFunction property of the OptimizerSADEA object. The evaluation function used in this example is defined at the end of this example.

s = OptimizerSADEA(Bounds);
s.CustomEvaluationFunction = @customEvaluationOnlyObjective;

Run the optimization for 100 iterations.

figure
s.optimizeWithPlots(100);

View the best member data.

bestDesign = s.getBestMemberData

bestDesign = 
  bestMemberData with properties:

             member: [4.7998 0.1101]
       performances: -4.7895
            fitness: -4.7895
    bestIterationId: 50

bestdesignValues = bestDesign.member

bestdesignValues = 1×2

    4.7998    0.1101

Update the reference antenna with best design values from the optimizer. Calculate directivity of the optimized design.

Observe an increase in directivity value after optimization.

referenceAnt.Length = bestdesignValues(1);
referenceAnt.Width = bestdesignValues(2);
postOptimizationDirectivity = max(max(pattern(referenceAnt,75e6)))

postOptimizationDirectivity = 
4.7895

View the surrogate model data used for prediction.

InitialData = s.getInitializationData

InitialData = 
  initializationData with properties:

         members: [30×2 double]
    performances: [30×1 double]
         fitness: [30×1 double]

View the data for all iterations.

iterData = s.getIterationData

iterData = 
  iterationData with properties:

         members: [68×2 double]
    performances: [68×1 double]
         fitness: [68×1 double]

Check if the algorithm has converged.

ConvergenceFlag = s.isConverged

ConvergenceFlag = logical
   1

Check how many times the evaluation function is computed.

NumEvaluations = s.getNumberOfEvaluations

NumEvaluations = 
98

Plot the convergence trend.

s.showConvergenceTrend

Following code defines the evaluation function used in this example.

function fitness = customEvaluationOnlyObjective(designVariables)
    fitness = [];
    try
        % Create geometry
        ant = design(dipole,75e6);
        ant.Length = designVariables(1);
        ant.Width = designVariables(2);
    catch
        % Handle errors during geometry creation.
        % High penalty value is used to handle errors.
        fitness = 1e6;
    end
    
    if isempty(fitness)
        try
            % Calculate directivity
            % Optimizer always minimizes the objective hence reverse the sign to maximize gain.
            objective = max(max(pattern(ant,75e6)));
            objective = -objective; 
        catch
            % Handle errors during gain computation.
            % High penalty value is used to handle errors.
            objective = 1e6;
        end
        % As there are no constraints, fitness equals objective.
        fitness = objective;
    end
end

Input Arguments

obj — Optimizer

OptimizerSADEA object | OptimizerTRSADEA object

Optimizer, specified as an OptimizerSADEA or OptimizerTRSADEA object. The function optimizes the custom evaluation function associated with the optimizer object specified in obj.

Example: OptimizerSADEA

iterations — Number of iterations for optimization

positive integer

Number of iterations for optimization, specified as a positive integer.

Example: 100

Data Types: double

Output Arguments

opt — Optimized custom evaluation function parameters

OptimizerSADEA object | OptimizerTRSADEA object

Optimized custom evaluation function parameters, returned as an OptimizerSADEA or OptimizerTRSADEA object. Use the getBestMemberData function to access the optimization results.

Version History

Introduced in R2025a