C++求矩阵的逆程序代码(2)

C++求矩阵的逆程序代码

for (i=0;i<dim;i++) y[i][j] = col[i];

}

for (i=0;i<dim;i++)

for (j=0;j<dim;j++)

mat[i][j] = y[i][j];

free_matrix(y,0,dim-1,0,dim-1);

free_vector(col,0,dim-1);

free(indx);

}

void ludcmp(double **a, int n, int *indx, double *d)

{

int i,imax,j,k;

double big,dum,sum,temp;

double *vv;

vv = (double*)malloc((unsigned)(n*sizeof(double))); if (!vv)

{

fprintf(stderr,"Error Allocating Vector Memory\n"); exit(1);

}

*d = 1.0;

for (i=0;i<n;i++)

{

big = 0.0;

for (j=0;j<n;j++)

{

if ((temp=fabs(a[i][j])) > big) big = temp;

}

if (big == 0.0)

{

fprintf(stderr,"Singular Matrix in Routine LUDCMP\n"); for (j=0;j<n;j++) printf(" %f ",a[i][j]); printf("/n"); exit(1);

}

vv[i] = 1.0/big;

}

for (j=0;j<n;j++)

{

for (i=0;i<j;i++)

{

sum = a[i][j];

for (k=0;k<i;k++) sum -= a[i][k] * a[k][j];