/*
* engwindemo.c
*
* This program illustrates how to call MATLAB
* Engine functions from a C program on Windows.
*
* Copyright 1984-2017 The MathWorks, Inc.
*/
#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "engine.h"
#include <matrix.h>
#define BUFSIZE 256
static double Areal[6] = { 1, 2, 3, 4, 5, 6 };
int PASCAL WinMain (HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpszCmdLine,
int nCmdShow)
{
Engine *ep;
mxArray *T = NULL, *a = NULL, *d = NULL;
char buffer[BUFSIZE+1];
double *Dreal, *Dimag;
double time[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
/*
* Start MATLAB engine
*/
if (!(ep = engOpen(NULL))) {
MessageBox ((HWND)NULL, (LPSTR)"Can't start MATLAB engine",
(LPSTR) "Engwindemo.c", MB_OK);
exit(-1);
}
/*
* PART I
*
* For the first half of this demonstration, we will send data
* to MATLAB, analyze the data, and plot the result.
*/
/*
* Create a variable from our data
*/
T = mxCreateDoubleMatrix(1, 10, mxREAL);
/*
* Copy data from time to matrix T
*/
#if MX_HAS_INTERLEAVED_COMPLEX
memcpy(mxGetDoubles(T), time, 10*sizeof(double));
#else
memcpy(mxGetPr(T), time, 10*sizeof(double));
#endif
/*
* Place the variable T into the MATLAB workspace
*/
engPutVariable(ep, "T", T);
/*
* Evaluate a function of time, distance = (1/2)g.*t.^2
* (g is the acceleration due to gravity)
*/
engEvalString(ep, "D = .5.*(-9.8).*T.^2;");
/*
* Plot the result
*/
engEvalString(ep, "plot(T,D);");
engEvalString(ep, "title('Position vs. Time for a falling object');");
engEvalString(ep, "xlabel('Time (seconds)');");
engEvalString(ep, "ylabel('Position (meters)');");
/*
* PART II
*
* Create another mxArray, put it into MATLAB,
* and calculate its eigen values.
*
*/
a = mxCreateDoubleMatrix(3, 2, mxREAL);
/*
* Copy data from Areal to matrix a
*/
#if MX_HAS_INTERLEAVED_COMPLEX
memcpy(mxGetDoubles(a), Areal, 6*sizeof(double));
#else
memcpy(mxGetPr(a), Areal, 6*sizeof(double));
#endif
engPutVariable(ep, "A", a);
/*
* Calculate the eigen value
*/
engEvalString(ep, "d = eig(A*A')");
/*
* Use engOutputBuffer to capture MATLAB output. Ensure first that
* the buffer is always NULL terminated.
*/
buffer[BUFSIZE] = '\0';
engOutputBuffer(ep, buffer, BUFSIZE);
/*
* the evaluate string returns the result into the
* output buffer.
*/
engEvalString(ep, "whos");
MessageBox ((HWND)NULL, (LPSTR)buffer, (LPSTR) "MATLAB - whos", MB_OK);
/*
* Get the eigen value mxArray
*/
d = engGetVariable(ep, "d");
engClose(ep);
if (d == NULL) {
MessageBox ((HWND)NULL, (LPSTR)"Get Array Failed", (LPSTR)"Engwindemo.c", MB_OK);
}
else {
/*
* Using interleaved complex representation we can access complex number
* with a single pointer instead of using two separate pointers.
*/
#if MX_HAS_INTERLEAVED_COMPLEX
if (mxIsComplex(d)) {
sprintf(buffer,"Eigenval 2: %g+%gi",mxGetComplexDoubles(d)[1].real,mxGetComplexDoubles(d)[1].imag);
}
else {
sprintf(buffer,"Eigenval 2: %g",mxGetDoubles(d)[1]);
}
#else
Dreal = mxGetPr(d);
Dimag = mxGetPi(d);
if (Dimag) {
sprintf(buffer,"Eigenval 2: %g+%gi",Dreal[1],Dimag[1]);
}
else {
sprintf(buffer,"Eigenval 2: %g",Dreal[1]);
}
#endif
MessageBox ((HWND)NULL, (LPSTR)buffer, (LPSTR)"Engwindemo.c", MB_OK);
mxDestroyArray(d);
}
/*
* We're done! Free memory, close MATLAB engine and exit.
*/
mxDestroyArray(T);
mxDestroyArray(a);
return(0);
}
/* LocalWords: eigen eng Eigenval gi
*/
