Solving exponential equations in C++

Depends on what you mean by "exp"--what is this function supposed to do? Also, you can't assign a constant to anything but a constant, as far as I know. The entire expression must be a constant (unless x is a constant as well). Can you be a  bit more specific as to what exactly you're trying to accomplish?

He is trying to solve the equation "e^mx + e^nx = k" for x; m, n & k are known.

Excactly as jhshukla said.. Any ideas?

/* Newton's method example.
   http://en.wikipedia.org/wiki/Newton%27s_method */
#include <stdio.h>
#include <math.h>
 
/* the function */
#define f(x)	exp(2*x)+exp(3*x)-5
/* the derivative on x */
#define f_(x)	2*exp(2*x)+3*exp(3*x)
/* the first quess */
#define x0	-1
/* precision */
#define epsilon	1e-9
 
int main()
{
    double prev,curr,delta;
    prev=curr=x0;
    while(1)
    {
	curr = prev - (f(prev)/f_(prev));
	delta = fabs(curr-prev);
	printf(">> %.10f e=%.10f\n",curr,delta);
	if (delta < epsilon)
	  break;
	prev = curr;
    }
    printf("%.10f\n",curr);
    return 0;
}

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