/*

Create the n*n Hilbert Matrix

*/

# include "mex.h"

void hilb(double *y,int n)

{

    int i,j;

    for(i=0;i<n;i++)

        for(j=0;j<n;j++)

            *(y+j+i*n)=1/((double)i+(double)j+1);

}

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

{

         //x is the input param,y is the pointer to the matrix create in c

    double x,*y;

         //the size of the matrix

    int n;

         //only one param for input is allowed

    if (nrhs!=1)

        mexErrMsgTxt("One inputs required.");

         //only one param for output is allowed

    if (nlhs != 1)

        mexErrMsgTxt("One output required.");

         //the param inout must be a scaler which type is double

    if (!mxIsDouble(prhs[0])||mxGetN(prhs[0])*mxGetM(prhs[0])!=1)

        mexErrMsgTxt("Input must be scalars.");

         //get the size of matrix we want  to create

    x=mxGetScalar(prhs[0]);

         //create a x*x matrix,the element's datatype is real double,

         //and the matrix's pointer is associated with the firt output param.

    plhs[0]=mxCreateDoubleMatrix(x,x,mxREAL);

         //get the row numbers of the created matrix

    n=mxGetM(plhs[0]);

         //get the pointer of the created matrix

    y=mxGetPr(plhs[0]);

         //call subfunction

    hilb(y,n);

}