// ------------------------------------------------------
// force-bisector
// 
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <float.h>
// ------------------------------------------------------
double A, B, C, M, N;
double func(double x)
{
	return 
		A * exp(M*x) + B * exp(N*x) - C;
}
// -------------------------------------------------------
double ForceBiSector(double eps,
	double (*fx)(double),
	int max_itera)
{
	double low = -DBL_MAX;
	double up  =  DBL_MAX;
	double mid = 0.0;
	double ylow=fx(low), yup=fx(up), ymid=fx(mid);
	unsigned long long times=0;
	while(fabs(ymid) > eps && times < max_itera){
		if(ymid * yup < 0.0) ylow = ymid, low=mid;
		else yup = ymid, up=mid;
		mid  = 0.5 * (up+low);
		ymid = fx(mid);
		++times;
	}
	printf("\ntimes : %u\n", times);
	return mid;
}
 
// -------------------------------------------------------
int main()
{
	const double eps=1E-15;
	const int max_iterator=1000000;
	double x0, x;
 
	puts("A * e^(mx) + B * e^(nx) - C = 0 < force bisector >");
	printf("input A : "); scanf("%lf", &A);
	printf("input B : "); scanf("%lf", &B);
	printf("input C : "); scanf("%lf", &C);
	printf("input N : "); scanf("%lf", &N);
	printf("input M : "); scanf("%lf", &M);
 
	x = ForceBiSector(eps, func, max_iterator);
 
	printf("x       : %.15lf\n", x);
	printf("func(x) : %.15lf\n", func(x));
	// system("pause"); // 看不到結果, 這行加進去
	return 0;
}

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1
2
4
8
16

1.234
3.145
100.145
3.337
6.145

1000.247
123.597
12347.345
-10.2
-5.7