YTU 2421: C语言习题 矩形法求定积分

2421: C语言习题 矩形法求定积分

时间限制: 1 Sec  

内存限制: 128 MB

提交: 354  

解决: 234

题目描述

写一个用矩形法求定积分的通用函数，分别求

（说明: sin,cos,exp已在系统的数学函数库中，程序开头要用#include<cmath>）。

输入

输入求sin(x) 定积分的下限和上限 

输入求cos(x) 定积分的下限和上限

输入求exp(x) 定积分的下限和上限

输出

求出sin(x)的定积分 

求出cos(x)的定积分 

求出exp(x)的定积分

样例输入

0 1
0 1
0 1      

样例输出

The integral of sin(x) is :0.48
The integral of cos(x) is :0.83
The integral of exp(x) is :1.76      

提示

主函数已给定如下，提交时不需要包含下述主函数

/* C代码 */  

 int main()  

 {  

     float integral(float (*p)(float),float a,float b,int n);  

     float a1,b1,a2,b2,a3,b3,c,(*p)(float);  

     float fsin(float);  

     float fcos(float);  

     float fexp(float);  

     int n=20;  

     scanf("%f%f",&a1,&b1);  

     scanf("%f%f",&a2,&b2);  

     scanf("%f%f",&a3,&b3);  

     p=fsin;  

     c=integral(p,a1,b1,n);  

     printf("The integral of sin(x) is :%.2f\n",c);  

     p=fcos;  

     c=integral(p,a2,b2,n);  

     printf("The integral of cos(x) is :%.2f\n",c);  

     p=fexp;  

     c=integral(p,a3,b3,n);  

     printf("The integral of exp(x) is :%.2f\n",c);  

     return 0;  

 }  





 /* C++代码 */  

 int main()  

 {  

     float integral(float (*p)(float),float a,float b,int n);  

     float a1,b1,a2,b2,a3,b3,c,(*p)(float);  

     float fsin(float);  

     float fcos(float);  

     float fexp(float);  

     int n=20;  

     cin>>a1>>b1;  

     cin>>a2>>b2;  

     cin>>a3>>b3;  

     cout<<setiosflags(ios::fixed);  

     cout<<setprecision(2);  

     p=fsin;  

     c=integral(p,a1,b1,n);  

     cout<<"The integral of sin(x) is :"<<c<<endl;  

     p=fcos;  

     c=integral(p,a2,b2,n);  

     cout<<"The integral of cos(x) is :"<<c<<endl;;  

     p=fexp;  

     c=integral(p,a3,b3,n);  

     cout<<"The integral of exp(x) is :"<<c<<endl;  

     return 0;  

 }      

迷失在幽谷中的鸟儿，独自飞翔在这偌大的天地间，却不知自己该飞往何方……

#include <stdio.h>
#include <math.h>
float integral(float (*p)(float),float a,float b,int n)
{
    float s=0.0,i,w;
    w=(b-a)/n;
    for(i=a; i<=b; i+=w)
        s+=p(i+w)*w;
    return s;
}
float fsin(float a)
{
    return sin(a);
}
float fcos(float a)
{
    return cos(a);
}
float fexp(float a)
{
    return exp(a);
}
int main()
{
    float integral(float (*p)(float),float a,float b,int n);
    float a1,b1,a2,b2,a3,b3,c,(*p)(float);
    float fsin(float);
    float fcos(float);
    float fexp(float);
    int n=20;
    scanf("%f%f",&a1,&b1);
    scanf("%f%f",&a2,&b2);
    scanf("%f%f",&a3,&b3);
    p=fsin;
    c=integral(p,a1,b1,n);
    printf("The integral of sin(x) is :%.2f\n",c);
    p=fcos;
    c=integral(p,a2,b2,n);
    printf("The integral of cos(x) is :%.2f\n",c);
    p=fexp;
    c=integral(p,a3,b3,n);
    printf("The integral of exp(x) is :%.2f\n",c);
    return 0;
}