Problem with mxGetScalar in mex function cuda

Hi *,

i've three different files: main.m makeOperator.m makeOperator_A.cu

In main.m:

global DICTIONARY

load('data.mat');

A = makeOperator();

x = rand( size(A,2), 1, 'double' );

R = A*x;

In makeOperator.m:

classdef makeOperator

properties

methods

..

function v = mtimes( obj, x )

global DICTIONARY

..

v = makeOperator_A( DICTIONARY);

end

..

end

In makeOperator_A.cu:

void mexFunction(int nlhs, mxArray *plhs[],int nrhs, const mxArray *prhs[]) {

mxArray* tmp;

..

tmp = mxGetField(prhs[0],0,"nV");

nV = mxGetScalar(tmp);

..

}

DICTIONARY is in data.mat. DICTIONARY is a struct and nV is a field of a struct

Whit mxGetScalar(tmp) i obtain nV=0 instead of nV=72 that is the true value of nV saved in DICTIONARY.nV

Why?

Thanks,

Davide

Answer 1

[James Tursa]

If MATLAB prints out the value of 72 for nV just prior to the mex call, then that is what it is inside your mex function. So my guess is you are having a formatting issue with printing out the value inside your mex function. Check to make sure that the variable type of nV inside the mex function matches the print format. E.g., If nV is an int, use %d to print it out. If nV is a double, use %f to print it out. What is the code you are using to print out the value of nV inside the mex routine?

[davide]

it was the problem ... I was using %f to print an int

Thank you

Answer 2

[James Tursa]

Can you verify the value of DICTIONARY.nV just prior to making the mex call? E.g.,

display(DICTIONARY.nV);
v = makeOperator_A( DICTIONARY);

Answer 3

[davide]

Yes and matlab prints the exact Value of DICTIONARY.nV