使用mex和C可以加快算法的运行速度，mex文件包含一个入口函数如下：

c}%Qe7L$vIln%J0void mexFunction( int nlhs， mxArray *plhs[]，int nrhs， const mxArray *prhs[] )51Testing软件测试网6X{+vB7a!f7_)G

51Testing软件测试网~%h$GT)X7s Zj3K/m

入口函数有四个参数：prhs为mxArray结构体类型的指针数组，该数组的元素按顺序指向所有的输入参数；;pL0@0n8qE0

51Testing软件测试网B.NuCEM0@S?

nrhs为整数类型，它标明了输入参数的个数。51Testing软件测试网8[2A;B-~on9u-v

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plhs：为mxArray结构体类型的指针数组，该数组的元素按顺序指向所有的输出参数；rL4A2}ort~0

51Testing软件测试网K9R(e7@pD.xbq

nlhs：输出参数的个数+t:d{rx8E l9r9y0

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在入口程序完成两件事情：51Testing软件测试网!x0J+A@}OP:_6`]

5N&CY?|:B0第一：从输入的mxArray结构体中获得计算完毕的数据，然后在用户的子程序中加以使用,Xz`D7~`G0

DL(pq2r/}b!C2E]0第二：用户可以将计算完毕的结果返回给一个用于输出的mxArray结构体。51Testing软件测试网N9a#Sa.t f

51Testing软件测试网$R:FL ee,R/f&}2D

mex源文件的两个组成部分可以分为两个文件也可以放在一个文件中，必须包含mex.h头文件，该头文件包含matrix.h和一些以mex开头的子函数。51Testing软件测试网-i$\*v&\S['A"vR|E^

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51Testing软件测试网:S7xf;Gq"g*D~

下面举几个例子：u*|\X9k

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51Testing软件测试网%]#sn3\V0A

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lz5OR+M#E%rR0#include "mex.h"51Testing软件测试网/f.AoF6kON8e%D

/* 输入参数 */[ NT\3\4y3f0

:kF!d7VIin!k051Testing软件测试网Eg`o%g-l"k7Oj1J

#define MInput prhs[0]     51Testing软件测试网m^jx$j3uCL

/* 输出参数 */:eO,J"p i+E5jO0

R,w5k$V,I5PuYN06SX2w[8~0Hta-B0#define OUTM plhs[0]ub(\yDKf:XrE0

U m q%C1N7R6?#A)@0;sQSgM)f9@)ZL0void mexFunction( int nlhs, mxArray *plhs[],

,EI.I"HC0      int nrhs, const mxArray *prhs[] )

H6E5n3zUQ0         {51Testing软件测试网D/?'bWcQQ4t2M

int i,j,N,L;51Testing软件测试网S&b"{g_ Y(@&?

double *Input,*output;

5e%h3yk'o0   51Testing软件测试网hX6y~)yF

if (nrhs < 1)  51Testing软件测试网z.N;~}4j(S;FJF

{51Testing软件测试网j&z9X"?y#q4s

mexErrMsgTxt("至少需要一个参数！");51Testing软件测试网FXg q^J#}G

}

n6|{+gk([4|0        Input= mxGetPr(MInput); /*获取矩阵*/  51Testing软件测试网k+x@1[4Ga

N = mxGetM( MInput ); /*获取矩阵的行*/51Testing软件测试网ZQDJ^

L = mxGetN( MInput); /*获取矩阵的列*/51Testing软件测试网v;_H(b0{T.H

for( i=0;i

}6Uk{

{

_e~8X1i"D2n3i8|Ww0    for ( j=0;j

printf("%f ", Input[i+j*N]);/*若索引从1开始则变成i-1+(j-1)*N MATLAB 是按列存数据 */ 51Testing软件测试网*u%w8CB"CA|

printf("\n"); /*输出完一行，换行*/51Testing软件测试网'd0i[:c ?4d

}

KC ]gTK~'LX0    51Testing软件测试网^ w{W%U4K p-\

OUTM= mxCreateDoubleMatrix(N,L, mxREAL); /* 建立输出矩阵*/

[6aP!p*\0 output=mxGetPr(OUTM);

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k.OlCwu0  for( i=0;i

4EM~"v:@J,c0{

4{Q0`%\;H/I$f0    for ( j=0;j

1u7T)['PZD#q]Vn0Ad

G0    output[i+j*N]=Input[i+j*N];/*若索引从1开始则变成i-1+(j-1)*N*/

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下面是字符串的操作：51Testing软件测试网

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"qpJ@8\L0Z9Iz0Vo:[3Z?I$sk0JzlB|9`J^0#include "mex.h"51Testing软件测试网 x-Y&Hm}S%e

^o7q*H3ReeP.Y0void51Testing软件测试网Q-GV"?t|-RT7k(IV

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

u|t}2u3o0xU/kx0{51Testing软件测试网z0~XSDH!u%j

char *buf;51Testing软件测试网f1Ss1Gq

mwSize buflen;51Testing软件测试网8B*Gc9k^B"vU

int status;51Testing软件测试网x;eu!T

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E](H*n!Qvz0(void) plhs;    /* unused parameters */

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7wOOeZ}mO0    /* Check for proper number of input and output arguments */

f&L$} w:cp)]F0    if (nrhs != 1) { 51Testing软件测试网!m Y6Jibs

mexErrMsgTxt("One input argument required.");

OnZ2cv*H*?M0    } 51Testing软件测试网GcDW4p*x

if (nlhs > 1) {51Testing软件测试网3L^ j8}B&c

C

mexErrMsgTxt("Too many output arguments.");51Testing软件测试网9oYzA9Qb

}

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];ttQW.FR0    /* Check for proper input type */51Testing软件测试网m/xd1u)[#i V

if (!mxIsChar(prhs[0]) || (mxGetM(prhs[0]) != 1 ) )  {

.M;a:poRL0 mexErrMsgTxt("Input argument must be a string.");51Testing软件测试网R'X

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}51Testing软件测试网^-A(O%iUMy

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/* Find out how long the input string is.  Allocate enough memory

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D0       to hold the converted string.  NOTE: MATLAB stores characters51Testing软件测试网-Lj,m7Yyb&bo

as 2 byte unicode ( 16 bit ASCII) on machines with multi-byte

W|n^v;y/UD0       character sets.  You should use mxChar to ensure enough space

4iLN}J0       is allocated to hold the string */

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8XSsvR/]3c0    buflen = mxGetN(prhs[0])*sizeof(mxChar)+1;51Testing软件测试网-vRg(?A/l

buf = mxMalloc(buflen);51Testing软件测试网 F/e*T#JGniT

,ld;]4hmG0    /* Copy the string data into buf. */ 51Testing软件测试网,lr7{+?+_C#u%Q'U

status = mxGetString(prhs[0], buf, buflen);   51Testing软件测试网*Z.Z6X0GuL

mexPrintf("The input string is:  %s\n", buf);51Testing软件测试网C5]|0^7LP

/* NOTE: You could add your own code here to manipulate 51Testing软件测试网'Jv`8ci tc

the string */

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9wEH$Z%}9ZQ0    /* When finished using the string, deallocate it. */

5U-M9YoIdoVC0    mxFree(buf);

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0],w8V9v-f*H0动态分配内存的例子：v)Xo%S2gsKx0

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51Testing软件测试网5X0J;Ef?*e"I%SSc`{f%s4`{0#include "mex.h"oB-QMF0

\M-UJVL0/* The mxArray in this example is 2x2 */51Testing软件测试网E#J5ps!_Qc

#define ROWS 2

?f~rl-X8Y&a0#define COLUMNS 251Testing软件测试网&b+T$M/yzUc

#define ELEMENTS 451Testing软件测试网gRFe6q

51Testing软件测试网&u#Y7FW:z$PI O ]!nN

void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {51Testing软件测试网L4Wrq,K:{

double  *pointer;          /* pointer to real data in new array */51Testing软件测试网j.QmjH+X5Q

double  *dynamicData;      /* pointer to dynamic data */

~t.O?.eB!k#TE0    const double data[] = {2.1, 3.4, 2.3, 2.45};  /* existing data */

:q`G~,f:XgpEC0    mwSize index;51Testing软件测试网(u2z?zx)a"jC

51Testing软件测试网Q-E@4A#g~"}X

/* Check for proper number of arguments. */

?#PP'koV0    if ( nrhs != 0 ) {

\#KR6Hl@a8@0        mexErrMsgIdAndTxt("MATLAB:arrayFillGetPrDynamicData:rhs","This function takes no input arguments.");51Testing软件测试网V9]/x};f`?\

}51Testing软件测试网{&vp G3C3gY/f

JOTO9Q(_/Y.CY0/* Create a local array and load data */

C^ a9J?1\)k0    dynamicData = mxMalloc(ELEMENTS * sizeof(double));

9E6M,e6Bee,s%t,\0    for ( index = 0; index < ELEMENTS; index++ ) {51Testing软件测试网 yus#Hyy N8v*K

dynamicData[index] = data[index];51Testing软件测试网9hadW]7{'Nr-[

}51Testing软件测试网6vk3V%h \V)cn!M'o

c5z;z0w1l*|s |c0/* Create a 2-by-2 mxArray; you will copy existing data into it */

9E o9^7p C_?0    plhs[0] = mxCreateNumericMatrix(ROWS, COLUMNS, mxDOUBLE_CLASS, mxREAL);51Testing软件测试网X`'M;y,V#pa8N3KC

pointer = mxGetPr(plhs[0]);51Testing软件测试网JNF

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51Testing软件测试网}r]4j!D,W?*|a

/* Copy data into the mxArray */

,qB _3]AR0    for ( index = 0; index < ELEMENTS; index++ ) {

.m{w$gq/MF0        pointer[index] = dynamicData[index];

7j'kQE9N){{AN0    }51Testing软件测试网{|9]Kr

/xb!LhCe0/* You must call mxFree(dynamicData) on the local data.

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Bd0       This is safe because you copied the data into plhs[0] */

dQ&`3w0_A {d0    mxFree(dynamicData);

"w4OkJF zu@G0    51Testing软件测试网&Kl4ow]:hFiGOK8To

return;

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