Alan Weiss

Last seen: 1 dag ago

MathWorks

2.084 total contributions since 2011

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
what is the maximum population size handled by GA ? What are your advices for large MINLP problems?
General MINLP with over 100 variables are not solvable globally. How can I make this blanket statement? For a general MINLP with...

1 dag ago | 0

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fitcsvm cross-validation
As shown in this doc example, the cross-validation loss is reported at the command line and plotted by default (I see that you t...

1 dag ago | 0

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Start genetic algorithm more than once until solution is found
Of course, just write a loop. runon = true while runon % Call ga with option set to stop early if necessary % If you didn't ...

1 dag ago | 0

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This is for two variable optimization problem using conjugate gradient method but I need to modify the provided code below so that I can check any function having more than two variable lets say 5 variables. Please help me I am new in matlab.
See my answer here: https://www.mathworks.com/matlabcentral/answers/801106-someone-please-help-me-i-have-made-a-2-variable-code...

1 dag ago | 0

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someone please help me. I have made a 2 variable code for optimization, I want code for "n" no. of variables.
It is probably a bit easier to write code for NUMERIC minimizaton of an arbitrary-sized expression than a hybrid SYMBOLIC minimi...

4 dagen ago | 0

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Writing complicated equations for problem-based optimization
I think that you need to keep clear in your mind (and code) what is an optimization variable and what is an optimization express...

4 dagen ago | 0

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3D Scatterplot and Pareto Front visualization
Did you try the scatteredinterpolant code from the answer? Modify it for your data: F = scatteredInterpolant(numbers(:,1),numbe...

5 dagen ago | 0

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Nonlinear Constraints in Multijob optimization
Your constraints can be formulated as nonlinear constraints. Make sure that you read and follow the note on that page. Alan Wei...

9 dagen ago | 0

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Error with lsqnonlin : Error in lsqncommon (line 14) if any(~isfinite(initVals.F))
Apparently, some initial values are not finite. You gave a value of x0 so that your objective function evaluated at x0 gives som...

11 dagen ago | 0

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Answered
Initial population in genetic algorithm
To get reproducible results, set the random number generator before you call ga. For example, rng default % or rng(1) or whate...

12 dagen ago | 0

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Answered
how to solve this error: objective function is returning undefined values at initial point. fsolve cannot continue.
I suggest that you learn to use the debugger. I put a break point in the solve_nch function, and found that at the first functio...

12 dagen ago | 1

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Matrix array in ga
I think that you are making a mistake by choosing the bitstring data type. Doing so loses the possibility of having constraints ...

17 dagen ago | 0

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Optimisation Tool GA Custom Plot
Perhaps if you put the names of the functions in curly braces {} you would have success: {@gaplotbestf,@gaplotchange} But come...

17 dagen ago | 0

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How can we insert upper and lower bounds in particle swarm optimization for more than one variable parameters that need to be optimized.
I am not sure that I understand you. You might be asking about bounding some control variables. Generally, all of your control v...

18 dagen ago | 1

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How can we get the surrogate function after the optimisation?
The surrogate model is not available, sorry. Indeed, its quality as a surrogate is unknown, and may be poor. Can you please say...

23 dagen ago | 0

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Nonlinear fitting: how do I split the linear and the nonlinear problems?
You should follow the example more closely. In the example the lambda variables only are declared to be optimization variables; ...

23 dagen ago | 1

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why does this code give an error ( Undefined function or variable 'ObjectiveFunction'. Error in psi_kozhin (line 44) Swarm.Particles(k).O = fobj(currentX); )?
I do not see where you defined ObjectiveFunction. Is it on your MATLAB path? Alan Weiss MATLAB mathematical toolbox documentat...

ongeveer een maand ago | 0

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Find minimum of multi-variable function on fixed interval with additional parameter inputs
You need to pass the parameters correctly. See Passing Extra Parameters. In your case, you need to either nest the function in a...

ongeveer een maand ago | 0

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Answered
Genetic Algorithm: Plot ONLY best fitness value, not mean.
You could try using this slightly modified plot function, gaplotbestf2: (I modified it slightly from gaplotbestf) function stat...

ongeveer een maand ago | 0

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Fitting nonlinear noisy data
Most likely the issue is that there are multiple local minima, as in this example: Nonlinear Data-Fitting Using Several Problem-...

ongeveer een maand ago | 1

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Explanation of hyperparameter tuning procedure for regression tree ensembles
You can find all the information later on in that same reference page: Hyperparameter Optimization Options Alan Weiss MATLAB ...

ongeveer een maand ago | 0

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Fitting procedure using MultiStart - doesn't recognize objective function
I think that you need to have just one input variable, typically called x, and have each of your other named variables be a comp...

ongeveer een maand ago | 0

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Optimization toolbox with ode45
I guess that I would make a minimization problem for Y(end,2)^2. I don't know what your parameters are, but you can use fminbnd ...

ongeveer een maand ago | 0

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Surrogate Optimization Error: 'Dimensions of arrays being concatenated are not consistent'
You say "Do not mind the AdiabaticReactor function" but I cannot tell what sizes the inputs and outputs are for the objconstrAdi...

ongeveer een maand ago | 0

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Error: Complex values are not supported
I don't know where your objective function creates complex values, though I suspect that one or more of your logarithm calls has...

ongeveer een maand ago | 0

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How to find optimum complex weighting coefficients for antenna beam pattern optimisation? A purely optimisation problem
fmincon requires real values only. Convert your complex-valued problem to twice as many real variables. For an example, see Fit ...

ongeveer een maand ago | 0

Answered
system of nonlinear equations
Do you have Optimization Toolbox™ installed? Check by running the ver command. You might need to install or reinstall. Alan Wei...

ongeveer een maand ago | 0

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Answered
Nonlinear fitting depends too heavily on starting points
You might find some relevant information here or here. The point is that fitting problems typically have multiple local optima, ...

ongeveer een maand ago | 0

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Answered
Genetic Algorithm to Find desired parameters.
You might want to spend a little time reading up on the genetic algorithm: Genetic Algorithm Terminology How the Genetic Algor...

ongeveer een maand ago | 0

Answered
I am working on an optimization problem which has 60 optimization variables to get minimum objective function. which solver would be best for this problem? right now I am using multistart with fmincon.
If your problem is smooth and you are looking for a global minimum, then those sound like the right choices, See Table for Choos...

ongeveer een maand ago | 2