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Alan Weiss

MathWorks

Last seen: 1 day ago |  Active since 2011

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I write documentation for MATLAB mathematical toolboxes, primarily optimization. I have also written documentation for PDE, statistics, symbolic math, and econometrics.

My pre-MathWorks job was with Bell Labs, primarily in mathematical models of data traffic, with a strong interest in parallel computation and in rare events (large deviations).

I do not provide private consulting. If you have a question, please ask on a public forum such as MATLAB Answers.

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Answered
How to plot non-quadratic functions?
This sounds like a multiobjective optimization problem. See Generate and Plot Pareto Front and, if you have Global Optimization ...

5 days ago | 0

Answered
How do I iterate f(x)
Is this what you are looking for? f = @(x)exp(x) - 2 - x - x.^2./2; t = linspace(0,5); plot(t,f(t)) OK, there is a root in t...

9 days ago | 0

Answered
How do I solve this system of non-linear equations using fsolve?
I don't know if this is helpful, but I suspected that fsolve was having trouble because of the scaling of your variables; everyt...

10 days ago | 0

Answered
How to display the value of a specific component of the objective function after computation is done?
I'd be very interested to know what you think of the nuclear fuel disposal example. But to answer your question, let's look at ...

13 days ago | 0

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Answered
How to make the initial population in genetic algorithm fixed?
In addition to what Walter said, you can set the global random seed. rng default % Or rng(seed) [x,fval] = solve(problem,"Solv...

16 days ago | 1

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Answered
Setting Pareto FronI want to set the Pareto Front using genetic algorithm
You can take a larger population. For example, options = optimoptions('gamultiobj','PopulationSize',300); Make sure to pass op...

25 days ago | 0

Answered
Gamultiobj takes too long to run. Is there a workaround?
I am sorry, but I do not have time to understand your model in detail. However, I notice that you are using the problem-based ap...

1 month ago | 0

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Answered
how to solve a multi-objective nonlinear optimization problem with constraints ?
For an example that optimizes the solution of an ODE using optimization variables, see Fit ODE Parameters using Optimization Var...

1 month ago | 0

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Answered
Which optimization method is better for problems with random steps
In addition to what the other answerers have described, there does exist an optimization solver that can deal with stochastic ob...

1 month ago | 0

Answered
Optimization problem code sos please help
Have you seen the Problem-Based Optimization Workflow? This approach allows you to create optimization variables as symbolic-typ...

1 month ago | 0

Answered
how to use parfor for optim constraints?
Unfortunately, your version of Optimization Toolbox does not have the latest upgrade which uses "static analysis" to speed the c...

1 month ago | 1

Answered
On which data is the ML model trained after hyperparameter optimization /Application of trained ML on new training data
With the settings you show, the software does not perform any cross validation. You need to set the OptimizeHyperparameters argu...

2 months ago | 1

Answered
What is the output when Particle Swarm Optimization exceeds MaxTime
I believe that the code returns the point giving the best (lowest) objective function value encountered. Alan Weiss MATLAB mat...

3 months ago | 0

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Answered
Genetic algorithm only works with integer constraints..
Yakov, your report indicates that the nonlinearly-constrained problem is being solved in the usual way: having very few iteratio...

4 months ago | 1

Answered
why doesn't the gamultiobj function give me the output of the algorithm?
Your script worked for me. I attach the result. Using these commands, I also got a plot of the Pareto front. opts = optimoption...

5 months ago | 0

Answered
GA - objective and constraints have to run the same expensive function
This is a difficult problem because of the way that ga calls functions, both fitness and nonlinear constraint. For most solvers,...

5 months ago | 0

Answered
A problem in official website 'Least-Squares (Model Fitting) Algorithms'
Thank you for pointing out this long-standing error in the documentation. I will fix the error as soon as practicable. Alan Wei...

5 months ago | 0

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Answered
Why is fmincon not finding the right solution?
Your mistake is trying to use fmincon to solve a problem with integer constraints. fmincon does not apply to this type of proble...

6 months ago | 0

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Answered
What does useParallel doesn't work with Automatic Differentiation means and how do I fix it?
This is not a problem, this is a notification from internal algorithms. You are using the problem-based approach with supported ...

6 months ago | 0

Answered
Spacecraft trajectory optimization with GA in Matlab (on/off constant thrust)
You might be interested in this example: Discretized Optimal Trajectory, Problem-Based. The problem formulation is different tha...

6 months ago | 0

Answered
I want to find 4 constant with used 1 eq
This is an underdetermined problem, meaning there are many different values of x1, x2, x3, and x4 that work. For example, choose...

6 months ago | 0

Answered
Trouble with plotting iterations in patternsearch optimization
I think that what is going on is that you have nonlinear constraints in your problem. When there are nonlinear constraints, patt...

6 months ago | 0

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Answered
Setting conditions for optimization variables
x = optimvar('x', 100, 'LowerBound', 0); ub = Inf(100,1); ub(1:10) = zeros(10,1); x.UpperBound = ub; showbounds(x) It would...

6 months ago | 0

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Answered
Supplying gradient for the subset of parameters
The short answer is no: there is no provision to provide analytic gradients for a subset of the parameters. I cannot think of a ...

6 months ago | 0

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Answered
Is there a way to specify objective and constraint gradients when doing nonlinear optimization in the problem-based framework?
The problem-based approach calculates and uses gradients automatically for supported functions. However, to include gradients of...

6 months ago | 0

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Answered
surrogateopt: output function
Try this. lb = [-3 -3]; ub = -lb; opts = optimoptions('surrogateopt','OutputFcn',@listout); obj = @(x)100*(x(2) - x(1)^2)^2 ...

6 months ago | 1

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Answered
Passing values to PSO options
It works for me. Here is a little test script: fun = @(x)x(1)*exp(-norm(x)^2); lb = [-5,-5]; ub = -lb; opts = optimoptions('...

6 months ago | 1

Answered
Do I need to normalize input parameters to Particle Swarm Optimization?
You don't usually need to scale your parameters, but many problems are solved more reliably if you do. See Center and Scale Your...

6 months ago | 0

Answered
Possible bug with coneprog?
I think that you have identified a problem with the default options for trajectory problems: the optimality tolerance should be ...

6 months ago | 0

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Answered
How can I save the output parameters for each step using lsqnonlin function?
Write an output function to save the values, either to a workspace variable or to a file. For syntax details, see Output Functio...

6 months ago | 0

| accepted

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