d12r2.cpp

VC++常用数据算法集,里面包含了大量的常用算法程序,很有用的哟!

#include <iostream.h>
#include <math.h>
#include <iomanip.h>
#include <stdlib.h>
#include <fstream.h>
#include <string>
#include <process.h>
#include<stdio.h>

int cint(double x)
{
	int temp;
	double iprt;
	if (x>0)
	{
	x=modf(x,&iprt);
		if(fabs(x)<0.5)
			temp=int(iprt);
		else
			temp=int(iprt+1);
	}
	else if(x==0)
		temp=0;
	else
	{
		x=modf(x,&iprt);
		if(fabs(x)<0.5)
			temp=int(iprt);
		else
			temp=int(iprt)-1;
	}
		return temp;
}

void prntft(double data[], double nn2)
{
	int n,m,mm;
    cout<<"n  real(n)  imag.(n)  real(N-n)  imag.(N-n)"<<endl;
    cout<<setw(1)<<"0";
	cout<<setw(14)<<data[1];
	cout<<setw(14)<<data[2];
	cout<<setw(14)<<data[1];
	cout<<setw(14)<<data[2]<<endl;
    for (n = 3; n<=(nn2 / 2) + 1; n=n+2)
	{
        m = (n - 1) / 2;
        mm = nn2 + 2 - n;
		cout<<setiosflags(ios::fixed);
		cout<<setprecision(0)<<setw(1)<<m;
		cout<<setprecision(6)<<setw(14)<<data[n];
		cout<<setprecision(6)<<setw(14)<<data[n+1];
		cout<<setprecision(6)<<setw(14)<<data[mm];
		cout<<setprecision(6)<<setw(14)<<data[mm+1]<<endl;
    }
}

void main()
{
    //program d12r2
    //driver for routine twofft
	int n,i,n2,isign;
    double data1[33], data2[33], fft1[65], fft2[65],per,x;
    n = 32;
    n2 = 2 * n;
    per = 8.0;
    const double pi = 3.1415926;    
    for( i = 1; i<=n; i++)
	{
        x = 2.0 * pi * i / per;
        data1[i] = cint(cos(x));
        data2[i] = cint(sin(x));
    }
    twofft(data1, data2, fft1, fft2, n);
    cout<<setw(1)<<"Fourier transform of first function:"<<endl;
    prntft(fft1, n2);
    cout<<setw(1)<<"Fourier transform of second function:"<<endl;
    prntft(fft2, n2);
    //invert transform
    isign = -1;
    four1(fft1, n, isign);
    cout<<setw(1)<<"Inverted transform = first function:"<<endl;
    prntft(fft1, n2);
    four1(fft2, n, isign);
    cout<<setw(1)<<"Inverted transform = second function:"<<endl;
    prntft(fft2, n2);
}