void svbksb(double u[], double w[], double v[], int m, int n, double b[], double x[])
{
    double tmp[100];
	int i,j,jj;
	double s;

    for (j = 1; j<=n; j++)
	{
        s = 0.0;
        if (w[j] != 0.0)
		{
            for (i = 1; i<=m; i++)
			{
                s = s + u[(i-1)*n+j] * b[i];
            }
            s = s / w[j];
        }
        tmp[j] = s;
    }
    for (j = 1; j<=n; j++)
	{
        s = 0.0;
        for (jj = 1; jj<=n; jj++)
		{
            s = s + v[(j-1)*n+jj] * tmp[jj];
        }
        x[j] = s;
    }
}