d7r6.cpp

数值计算c++源代码,包括各种算法。很有用的。

#include "iostream.h"
#include "fstream.h"
#include "stdlib.h"

void indexx(int n, double arrin[], int indx[])
{
	int i,j,l,ir,indxt;
	double q;
    for (j = 1; j<=n; j++)
	{
        indx[j] = j;
    }
    if (n == 1)
	{
		return;
	}
    l = int(n / 2 + 1);
    ir = n;
    do
	{
		if (l > 1)
		{
			l = l - 1;
			indxt = indx[l];
			q = arrin[indxt];
		}
		else
		{
			indxt = indx[ir];
			q = arrin[indxt];
			indx[ir] = indx[1];
			ir = ir - 1;
			if (ir == 1)
			{
				indx[1] = indxt;
				return;
			}
		}
		i = l;
		j = l + l;
		while (j <= ir)
		{
			if (j < ir)
			{
            	if (arrin[indx[j]] < arrin[indx[j + 1]])
				{
					j = j + 1;
				}
			}
			if (q < arrin[indx[j]])
			{
				indx[i] = indx[j];
				i = j;
				j = j + j;
			}
			else
			{
				j = ir + 1;
			}
		}
		indx[i] = indxt;
    }while(1);
}

void main()
{
    //program d7r6
    //driver for routine indexx 
    double a[101];
	int indx[101];
	int i,j;
	ifstream fin;
	fin.open("d:\\vc常用数值算法集\\data\\tarray.dat",ios::in|ios::nocreate);
	if (!fin)
	{
		cerr<<"could not open d:\\vc常用数值算法集\\data\\tarray.dat"<<endl;
		exit(1);
	}
	for (i=1; i<=100; i++)
	{
		fin>>a[i];
	}
	fin.close();
    //generate index for sorted array
    indexx(100, a, indx);
    //print original array
    cout<<"Original array:"<<endl;
	cout<<endl;
    for (i = 1; i<=10; i++)
	{
        for (j = 1; j<=10; j++)
		{
			cout.width(7);
			cout.setf(ios::left);
            cout<<a[10 * (i - 1) + j];
        }
        cout<<endl;
    }
    //print sorted array
	cout<<endl;
    cout<<"Sorted array:"<<endl;
    for (i = 1; i<=10; i++)
	{
        for (j = 1; j<=10; j++)
		{
			cout.width(7);
			cout.setf(ios::left);
            cout<<a[indx[10 * (i - 1) + j]];
        }
        cout<<endl;
    }
}