d5r9.cpp

visual c++查过能用数值算法 附带光盘里面的源代码

#include "iostream.h"
#include "math.h"

double func(double x)
{
    return (x * x) * (x * x - 2.0) * sin(x);
}

void main()
{
    //program d5r9
    //driver for routine pcshft
    int nval = 40;
    double a,b,x,poly,pio2 = 1.5707963;
    double c[41], d[41];
    a = -pio2;
    b = pio2;
    chebft(a, b, c, nval);
    cout<<endl;
    cout<<"How many terms in chebyshev evaluation?"<<endl;
    //input mval , between 6 and 40, mval=0 to end
    int mval = 20;
    if ((mval <= 0) || (mval > nval))
	{
		return;
	}
    cout<<mval<<endl;
    chebpc(c, d, mval);
    pcshft(a, b, d, mval);
    //test shifted polynomial
    cout<<"        x          Actual     Polynomial"<<endl;
	cout.setf(ios::fixed|ios::right);
	cout.precision(6);
    for (int i = -8; i<=8; i++)
	{
        x = i * pio2 / 10.0;
        poly = d[mval];
        for (int j = mval - 1; j>=1; j--)
		{
            poly = poly * x + d[j];
        }
		cout.width(13);
        cout<<x;
		cout.width(13);
        cout<<func(x);
		cout.width(13);
        cout<<poly<<endl;
    }
}