Thread: x power y?

I made the following function to calculate x power y..
I'd like to upgrade it to make it possible to calculate even if y is decimal.. ex 2^3.456

is that possible?
Im not asking for full code just ideas..

Code:

double power(double pow, double from)	// x power y
{
      double temp =  from;
      if(pow > 0)
      {
	  --pow;				// x power 1 means x 1 time not 2 times !
	  for(int i = 0; i < pow; i++)	  temp *= from;	// temp = from x times
      }
      else if(pow < 0)	  
      {
	  --pow;					//  10/10 = 1 so must add 1..
	  for(int i = 0; i > pow; --i)	  temp /= from;	// temp = from divided x times
      }
      else if (pow == 0) temp = 1;			// x power 0 == 1
      return temp;
}

that is an option but id like to try to make it myself..

I finally decided to use math.h since I really dunno how to calculate it..
ex: 2^2.5=5.656854249

One way to calculate it yourseld is to use logarithms:

ln( x^y ) = y * ln(x)

x^y = e^( y*ln(x) )

In C++:

Code:

double myPower(double x, double y)
{
  return exp( y * log(x) );
}