这是使用二分法求解多项式方程的程序 [英] This is the program to solve polynomial equations using bisection method

问题描述

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
void bisect(float *p,int n,int a);
float value(float *p,int n,int a);
int main()
{
    int a,i;
    float *p;
    printf("enter the degree of the polynomial\n");
    scanf("%d",&a);
    p=(float *) malloc(a*sizeof(float));
    for(i=0;i<=a;i++)
    {
        printf("enter the coefficient of x^%d\n",i);
        scanf("%f",p+i);
    }
    for(i=-100;i<100;i++)
    {


        if(value(p,i,a)*value(p,i+1,a)<0)
        {
            bisect(p,i,a);
        }
    }
    return 0;
}
float value(float *p,int n,int a)
{
    float sum=0;
    int i;
    for(i=0;i<=a;i++)
    {
        sum=sum+*(p+i)*pow(n,i);
    }
    return sum;
}
void bisect(float *p,int n,int a)
{
    float j,k,l;
    int i;
    j=n;k=n+1;l=(j+k)/2;
    for(i=0;i<50;i++)
    {
        if(value(p,j,a)*value(p,l,a)<0)
        {
            j=j;k=l;l=(j+k)/2;
        }
       else if(value(p,l,a)*value(p,k,a)<0)
       {
           l=(l+k)/2;j=l;
       }
    }
    printf("the root of the equation is %f\n",l);
}

这是通过使用二分法完成的，我知道代码没有优化，我无法从我的算法中导出任何根，我想找出任何逻辑错误，因为我经过多次调查后都找不到。我想知道数据类型的等同是否有任何错误。提前谢谢。

This is done by using bisection method, and i know that the code isn't optimized , i am unable to derive any root from my algorithm though, i want to find out any logical errors as i could find none after much investigation. I would like to know if there is any fault with the equating of data types. thanks in advance.

推荐答案

如果您希望其他人查看您的代码，您必须使用合理的变量名称。请看一下： http://www2.lv.psu.edu/ ojj / courses / cmpsc-201 / numerical / bisection.html [ ^ ]



我不会给你代码，因为这是作业但是：



1.解决此问题：

If you want other people to look at your code you must use sensible variable names. Have a look at this: http://www2.lv.psu.edu/ojj/courses/cmpsc-201/numerical/bisection.html[^]

I won't give you code because this is homework but:

1. Fix this:

p=(float *) malloc(a*sizeof(float));
for(i=0;i<=a;i++)

2.严重 - 将声明更改为：

2. Critical - Change declaration to:

double value(float *p, double x, int a);

并修复实施。



3.另外：

and fix implementation.

3. Also:

double j,k,l;

4.主要内容

4. In main

#include <iostream>
using namespace std;

和

and

cin.ignore();
cin.get();

return 0;

使用link中的值作为测试。

Use values from link as your test.

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