C++求矩阵的逆程序代码(3)

C++求矩阵的逆程序代码

}

big = 0.0;

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

{

sum = a[i][j];

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

if ((dum=vv[i]*fabs(sum)) >= big) {

big = dum;

imax = i;

}

}

if (j != imax)

{

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

{

dum = a[imax][k];

a[imax][k] = a[j][k];

a[j][k] = dum;

}

*d = -(*d);

vv[imax] = vv[j];

}

indx[j] = imax;

if (a[j][j] == 0.0) a[j][j] = TINY;

if (j != n-1)

{

dum = 1.0 / a[j][j];

for (i=j+1;i<n;i++) a[i][j] *= dum; }

}

free(vv);

}

void lubksb(double **a, int n, int *indx, double *b) {

int i,ip,j,ii=-1;

double sum;

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

{

ip = indx[i];