matlab coder covert m-file to c++?

Question

I used MATLAB coder to covert M-file to cpp-file.

There generated problem when is building.

Expected either a logical, char, int, fi, single, or double. Found an mxArray. MxArrays are returned from calls to the MATLAB interpreter and are not supported inside expressions. They may only be used on the right-hand side of assignments and as arguments to extrinsic functions.

MATLAB code :

nms = sum(transpose(X).^2);
nms0=-1 * nms;
nms2=transpose(nms0);
nms3=transpose(X);
nms4=nms2*ones(1,n);
nms5=ones(n,1)*nms;
nms6=2*X*nms3;
nms7=zeros(150,150);

nms7=nms4-nms5; //This line is wrong

nms8=nms7 + nms6;
K = exp(nms8);

I want to know why code has been run correct in MATLAB,but it has error when is building

John Saunders · Accepted Answer · 2015-07-02 04:17:25Z

0

This error happens when you try to use result of extrinsic functions in expressions. In the code you provided is "n" or "X" the result of an extrinsic function? Even if they are not directly a result of an extrinsic function, they may have been computed based on data from other extrinsic functions.

One way to fix the problem is to help MATLAB coder convert these extrinsic data to known types. You can do that by pre-defining them with known data. For example,

coder.extrinsic('some_extrinsic_fcn');
y = zeros(10,1);
y = some_extrinsic_fcn();
y = y * 2;

In this case some_extrinsic_fcn should return a double precision vector with 10 elements. This resulting mxArray will be auto-converted and stored in y. Without the line "y = zeros(10,1);" y will be of mxArray type and the line "y = y * 2;" will cause an error.

edited Jul 2, 2015 at 4:17

John Saunders

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answered Apr 29, 2013 at 16:24

Navan

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