ddpoly.cpp

来自「工程算法 这是一个很有用的工程数值算法集锦」· C++ 代码 · 共 32 行

void ddpoly(double c[], int nc, double x, double pd[], int nd)
{
	int i,j,nnd;
    pd[1] = c[nc];
    for (j = 2; j<=nd; j++)
	{
        pd[j] = 0.0;
    }
    for (i = nc - 1; i>=1; i--)
	{
        if (nc + 1 - i < nd)
		{
           nnd = nc + 1 - i;
		}
        else
		{
           nnd = nd;
        }
        for (j = nnd; j>=2; j--)
		{
            pd[j] = pd[j] * x + pd[j - 1];
        }
        pd[1] = pd[1] * x + c[i];
    }
    double const1 = 2.0;
    for (i = 3; i<=nd; i++)
	{
        pd[i] = const1 * pd[i];
        const1 = const1 * i;
    }
}