engwindemo.c

matlab从入门到精通第13章书后源码对初学者很有帮助

/*
 *	engwindemo.c
 */

#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "engine.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 };

	/*
	   启动MATLAB引擎 
	 */
	if (!(ep = engOpen(NULL))) {
		MessageBox ((HWND)NULL, (LPSTR)"Can't start MATLAB engine", 
			(LPSTR) "Engwindemo.c", MB_OK);
		exit(-1);
	}

	/*
	 * PART I
	   将数据传送到MATLAB，分析数据绘制结果
	 */

	/* 
	   创建变量
	 */
	T = mxCreateDoubleMatrix(1, 10, mxREAL);
	memcpy((char *) mxGetPr(T), (char *) time, 10*sizeof(double));

	/*
	   将变量T输出到MATLAB工作空间
	 */
	engPutVariable(ep, "T", T);

	/*
	   计算时间函数distance = (1/2)g.*t.^2
	 * (g is the acceleration due to gravity)
	 */
	engEvalString(ep, "D = .5.*(-9.8).*T.^2;");

	/*
	   绘制结果
	 */
	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
	   创建另一个mxArray，并将其存入到MATLAB，计算特征值
	 */
	  
	 a = mxCreateDoubleMatrix(3, 2, mxREAL);         
	 memcpy((char *) mxGetPr(a), (char *) Areal, 6*sizeof(double));
	 engPutVariable(ep, "A", a); 

	 /*
	   计算特征值
	 */
	 engEvalString(ep, "d = eig(A*A')");

	 /*
	   使用engOutputBuffer捕获MATLAB输出，保证缓冲区以NULL结束
	 */
	 buffer[BUFSIZE] = '\0';
	 engOutputBuffer(ep, buffer, BUFSIZE);

	 /*
	   计算字符串，并将结果返回到输出缓冲区
	 */
	 engEvalString(ep, "whos");
	 MessageBox ((HWND)NULL, (LPSTR)buffer, (LPSTR) "MATLAB - whos", MB_OK);
	
	 /*
	   获得mxArray的特征值
	 */
	 d = engGetVariable(ep, "d");
	 engClose(ep);

	 if (d == NULL) {
			MessageBox ((HWND)NULL, (LPSTR)"Get Array Failed", (LPSTR)"Engwindemo.c", MB_OK);
		}
	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]);
		MessageBox ((HWND)NULL, (LPSTR)buffer, (LPSTR)"Engwindemo.c", MB_OK);
	    mxDestroyArray(d);
	} 

	/*
	   释放内存，关闭MATLAB引擎
	 */
	mxDestroyArray(T);
	mxDestroyArray(a);
	
	return(0);
}