Thread Subject: Engine not sending the correct data

I am trying to send an array of doubles from a C program
into a matlab function via the matlab engine.

No matter what I send it, the engine sets all my variables
to zero. as a test, I created an array of doubles ranging
from 1 to 1000, in equal steps of 1.

I then create the array as:

    //Create the Matlab variable that stors the times array
    timesArray = mxCreateDoubleMatrix(1,dataSize,mxREAL);
//The Array
    tmpPtr = mxGetPr(timesArray); //The Pointer
    
    //Copy dataset into myData
    memcpy((void *)tmpPtr, (void *)times, sizeof(times));

where times is my test array.

However, when I print out timesArray using:

engPutVariable(ep, "timesArrayMat", timesArray);
engEvalString(ep, "disp(num2str(timesArrayMat(50)))");
printf("Mandor\n %s... \n", buffer);

it shows me 0. I can do this for every value of timesArray
and I always get 0.

Any ideas?

Mike

"Michael Stachowsky" <mstachowsky@gmail.com> wrote in
message <fqrtlm$qfb$1@fred.mathworks.com>...
> I am trying to send an array of doubles from a C program
> into a matlab function via the matlab engine.
>
> Any ideas?
>
> Mike

I have taken your example statements and constructed a
complete engine example that does what I think you want.
It prints a non-zero value. I left the engine running
after the program ends. Hopefully you can use this to help
debug your code.

Side comment: I think you are doing too much work with
your engEvalString call. You don't need to "disp(num2str
(timesArrayMat(50)))". Since all output that MATLAB would
normally send to the console gets put into the buffer, you
can simply do this: "timesArrayMat(50)". The whole
business of converting the number to a string and
displaying it will happen automatically, since that is
what would normally happen at the MATLAB prompt for this
statement.

James Tursa

--------------------------------------------

#include <stdio.h>
#include <string.h>
#include "engine.h"

#define dataSize 1000
#define bufferlength 2000

int main()
{
    char buffer[bufferlength];
    double times[dataSize];
    mxArray *timesArray;
    double *tmpPtr;
    Engine *ep;
    int i;

    if( (ep = engOpen(NULL)) == NULL )
        return 1; // error
    engOutputBuffer( ep, buffer, bufferlength );

    for( i=0; i<dataSize; i++ )
        times[i] = (double) (i+1);

    timesArray = mxCreateDoubleMatrix( 1, dataSize,
mxREAL );
    if( timesArray == NULL )
        return 1; // error
    tmpPtr = mxGetPr( timesArray );
    memcpy( (void *)tmpPtr, (void *)times, sizeof(times) );

    if( engPutVariable( ep, "timesArrayMat", timesArray ) )
        return 1; // error
    engEvalString( ep, "disp(num2str(timesArrayMat
(50)))" );
    printf("mandor\n %s... \n", buffer );

    mxDestroyArray( timesArray );

    return 0;
}