讨论1.3 多项式求和

1题目 

2分析

3代码 

4运行结果 

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1题目 

2分析

3代码 

#include <iostream>
#include <ctime>
#include <cmath>
using namespace std;

clock_t start, stop;
const int MAXK = 1e5;
double duration;

double f1(double x);
double f2(double x);
void printFunTime(double (*p)(double x));

int main()
{
    printFunTime(f1);
    printFunTime(f2);
    system("pause");
    return 0;
}
void printFunTime(double (*p)(double x))
{
    double ret;
    start = clock(); //开始计时
    for (int i = 1; i < MAXK; i++)
        ret = p(1.1);
    stop = clock();
    duration = ((double)(stop - start)) / CLK_TCK / MAXK;
    cout << duration << "  " << ret << endl; //输出时间和结果
}
double f1(double x) //逐项求解
{
    double sum = 1.0;
    int i;
    for (i = 1; i <= 100; i++)
        sum += pow(x, i) / i;
    return sum;
}

double f2(double x) //合并
{
    double p = 1.0 / 100;
    int i;
    for (i = 99; i >= 1; i--)
        p = 1.0 / i + x * p;
    p = 1 + p * x;
    return p;
}

4运行结果