fsolve in codegen returns indexing error

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Max Bartholdt
Max Bartholdt 2020-11-18
评论： Max Bartholdt 2020-11-20
Hello,
I am struggling with the code generation of a function containing the fsolve command (supported since R2020b). Since it is a rather new topic, I did not find any related entries.
This is the function i try to generate the mex-file for:
function [x] = test_function(a,b)
%#codegen
x = zeros(1);
opts = optimoptions('fsolve','Algorithm','levenberg-marquardt','Display','off');
% opts = optimoptions(opts,a.string,a.val);
fcn = @(in)feval(b,in);
rng default
x0 = double(0.00);x(1) = fsolve(fcn,x0,opts);
end
And this is how I setup the code generation:
cfg = coder.config('mex');
types = coder.getArgTypes('mytest','test_function')
codegen -config cfg -args types test_function
With the following function to get the coder.Types:
function out = mytest
a.val = 10e-5;
a.string = "FunctionTolerance";
b = 'myeq';
out = test_function(a,b);
end
The struct a has no purpose yet, but will later be used to setup the optimoptions.
Error Message after calling the codegen:
"??? Index expression out of bounds. Attempted to access element 1. The valid
range is 1-0."
In the Coder Report Viewer it sais, that the error occured in function projectBox. I would appreciate any thoughts on this.
Many Regards,
Max
  3 个评论
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Mukund Sankaran
Mukund Sankaran 2020-11-18
Hi Max. Would it be possible for you to share the code for myeq ?
Max Bartholdt
Max Bartholdt 2020-11-19
编辑：Max Bartholdt 2020-11-19
function x = myeq(u)
x = zeros(1,1);
u1 = u(1);
% u2 = u(2);
x(1) = (u1^2-u1)-3;
% x(2) = u2*u1+2;
end

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采纳的回答

Caleb Magruder
Caleb Magruder 2020-11-19
Hi Max,
Unfortunately, this is due to a bug which will be fixed in an upcoming software update.
In the meantime, you can work around the issue by calling lsqnonlin instead of fsolve and pass -Inf as a lower bound and Inf as an upper bound, effectively making the problem unbounded. You will also need to update the optimoptions solver from 'fsolve' to 'lsqnonlin' in line 4 of test_function. The updated test_function is below for your reference.
We apologize for the inconvenience this has caused and appreciate you bringing it to our attention.
function [x] = test_function(a,b)
%#codegen
x = zeros(1);
opts = optimoptions('lsqnonlin','Algorithm','levenberg-marquardt','Display','off');
% opts = optimoptions(opts,a.string,a.val);
fcn = @(in)feval(b,in);
rng default
x0 = double(0.00);x(1) = lsqnonlin(fcn,x0,-Inf,Inf,opts);
end
  1 个评论
Max Bartholdt
Max Bartholdt 2020-11-20
Hello Caleb,
Thank you for your quick answer and the suggestion for a workaround.
Many Regards,
Max

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