eulsum.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 eulsum(double& sum, double term, int jterm, double wksp[])
{
    static int nterm;
	double tmp,dum;
    if (jterm == 1)
	{
        nterm = 1;
        wksp[1] = term;
        sum = 0.5 * term;
	}
    else
	{
        tmp = wksp[1];
        wksp[1] = term;
        for (int j = 1; j<=nterm; j++)
		{
            dum = wksp[j + 1];
            wksp[j + 1] = 0.5 * (wksp[j] + tmp);
            tmp = dum;
        }
        if (fabs(wksp[nterm + 1]) <= fabs(wksp[nterm]))
		{
            sum = sum + 0.5 * wksp[nterm + 1];
            nterm = nterm + 1;
		}
        else
		{
            sum = sum + wksp[nterm + 1];
        }
    }
}