85 value polynomial calculated
Author: Turbo Time limit: 1S Section: cycling
Problem Description :
When the calculated value and outputs the following polynomial x <0.97, the absolute value is smaller than the threshold is reached until the last one (the polynomials are not included in the results).
image.png enter a description:
Input test data may be a plurality of sets, each row, each including two real numbers, the first of X (0.2≤x
<0.97), as a second threshold (≥0.000001), separated by a space.Output Description:
For each test, an output line, the calculated result, to retain six decimal places. There was no space before and after the result output. Is a blank line between the two operation results. Entry:
0.2 0.000001
0.21 0.000001 Output Example:
1.0954451.100000
Code:
/*
T85 计算多项式的值
*/
#include<stdio.h>
#include<math.h>
double frac(double);
double getNum(double);
double getXpower(double);
int main() {
double x = 0, threshold = 0, n = 1;
double sum = 1, item = 0;
int i = 0;
while (scanf("%lf %lf", &x, &threshold) != EOF) {
if (threshold > 1) {// 考虑特殊情况
printf("%lf\n\n", 0);
continue;
}
n = 1;
sum = 1;
while (1) {
item = (getNum(n - 1) / frac(n)) * pow(x, n);// 每一项的值
if (fabs(item) < threshold) {
printf("%lf\n\n", sum);
break;
}
sum += item;
n++;
}
}
return 0;
}
// 阶乘
double frac(double n) {
if (n == 1 || n == 0)
return 1;
return n * frac(n - 1);
}
// 计算分子
double getNum(double n) {
if (n == 0) {
return 0.5;
}
return (0.5 - n) * getNum(n - 1);
}