lubksb.c

来自「快速傅立叶变换程序代码,学信号的同学,可要注意了」· C语言 代码 · 共 21 行

void lubksb(float **a,int n,int *indx,float *b)
{
  int i,ii=0,ip,j;
  float sum;
  
  for (i=1;i<=n;i++) {
    ip=indx[i];
    sum=b[ip];
    b[ip]=b[i];
    if (ii)
      for (j=ii;j<=i-1;j++) sum -= a[i][j]*b[j];
    else if (sum) ii=i;
    b[i]=sum;
  }
  for (i=n;i>=1;i--) {
    sum=b[i];
    for (j=i+1;j<=n;j++) sum -= a[i][j]*b[j];
    b[i]=sum/a[i][i];
  }
}