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Is this a bug in lsqcurvefit?

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Catalytic
Catalytic on 29 Mar 2019
Commented: Matt J on 4 Apr 2019
When I run this simple test of lsqcurvefit (this is R2018a), I get errors.
opts=optimoptions(@lsqcurvefit,'SpecifyObjectiveGradient',true,...
'JacobianMultiplyFcn',@Jfun);
p=lsqcurvefit(@modelfun,2,10,11,[],[],opts)
function [y,Jinfo]=modelfun(p,xdata)
y=xdata-p;
Jinfo=0;
end
function out=Jfun(Jinfo,Y,flag)
out=0;
end
The errors are
Too many input arguments.
Error in lsqcurvefit/jacobmult (line 291)
W = feval(mtxmpy_xdata,Jinfo,Y,flag,XDATA,varargin{:});
Error in snls (line 199)
g = feval(mtxmpy,A,fvec(:,1),-1,varargin{:});
Error in lsqncommon (line 167)
snls(funfcn,xC,lb,ub,flags.verbosity,options,defaultopt,initVals.F,initVals.J,caller,
...
Error in lsqcurvefit (line 271)
lsqncommon(funfcn,xCurrent,lb,ub,options,defaultopt,allDefaultOpts,caller,...
Error in test1 (line 6)
p=lsqcurvefit(@modelfun,2,10,11,[],[],opts)
Looking at line 291 in lsqcurvefit shows that it is in fact trying to pass xdata as a 4th argument to the JacobMult function
function W = jacobmult(Jinfo,Y,flag,varargin)
W = feval(mtxmpy_xdata,Jinfo,Y,flag,XDATA,varargin{:});
end
I can see why it would make sense to pass xdata to the user-provided JacobMult function, in addition to Jinfo,Y, and flag, but nowhere in the documentation does it say to format the JacobMult function this way. Is this a coding bug or a documentation bug?
  1 Comment
Matt J
Matt J on 4 Apr 2019
Another question, sort of on the same subject. When the JacobianMutiplyFcn is used, what does the solver return for the jacobian output in the following?
[x,resnorm,residual,exitflag,output,lambda,jacobian] = lsqcurvefit(___)

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