Uva 10341 — Solve It

Solve the equation:
        p*e^-x+ q*sin(x) + r*cos(x) + s*tan(x) + t*x² + u = 0
        where 0 <= x <= 1.

Input

Input consists of multiple test cases and terminated by an EOF. Each test case consists of 6 integers in a single line: p, q, r, s, t and u (where 0 <= p,r<= 20 and -20 <= q,s,t <= 0). There will be maximum 2100 lines in the input file.

Output

For each set of input, there should be a line containing the value of x, correct upto 4 decimal places, or the string "No solution", whichever is applicable.

Sample Input

0 0 0 0 -2 1

1 0 0 0 -1 2

1 -1 1 -1 -1 1

Sample Output

0.7071

No solution

0.7554

题意：解方程，求出令上述方程为零的根；

分析：观察方程可知，右边部分为单调递减函数，所以可以二分查找函数，需注意数值精度；

#include<stdio.h>#include<string.h>#include<math.h>#define epsx 1e-7#define e   2.718281828459int p,q,r,s,t,u;double search(double a,double b){    double m=(a+b)/2;    if(b-a<epsx)return m;        double g=p*pow(e,-m)+ q*sin(m) + r*cos(m) + s*tan(m) + t*m*m + u;    if(g==0)        return m;    if(g>0)        return search(m,b);    if(g<0)        return search(a,m);}int main(){    while(scanf("%d%d%d%d%d%d",&p,&q,&r,&s,&t,&u)!=EOF)    {        if(p*pow(e,-0)+ q*sin(0) + r*cos(0) + s*tan(0) + t*0*0 + u<0||p*pow(e,-1)+ q*sin(1) + r*cos(1) + s*tan(1) + t*1*1 + u>0)        {   printf("No solution\n");continue; }                    else            printf("%.4lf\n",search(0,1));    }    return 0;}