d6r9.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 45 行

#include <iostream.h>
#include <math.h>
#include <iomanip.h>
#include <stdlib.h>

void main()
{
    //program d6r9
    //driver for routine bnldev
    int idum,n = 20, npts = 10000, iscal = 200, llen = 50,nn=100;
	int xm,klim,i,j,k,m;
    double pp,dist[21];
	char text[50];
    idum = -133;
    for (j = 1; j<=20; j++)
        dist[j] = 0.0;
    cout<<"Mean of Binomial distribution [n=1..20] -1 to end."<<endl;
    xm = 5;
    cout<<xm<<endl;
    if (xm <= 0) exit(1);
	pp=double(xm)/double(nn);
	for (i = 1; i<=npts; i++)
	{
        j = int(bnldev(pp,nn, idum));
        if ((j >= 0) && (j <= 20)) dist[j+1] = dist[j+1] + 1;
    }
    cout<< "    x     p[x]     graph:"<<endl;
    for (j = 1; j<=20; j++)
	{
        dist[j] = dist[j] / npts;
        for (k = 0; k<=50; k++)
            text[k] =' ';
        klim = int(iscal * dist[j]);
        if (klim > llen) klim = llen;
        for (k = 1; k<=klim; k++)
            text[k] = '*';
        cout<< setw(5)<<float(j-1);
        cout<< setw(10)<<dist[j]<<"    ";
        
        for (m = 1; m<=50; m++)
            cout<< text[m];
		cout<<endl; 
     }
}