Pi approximation with Archimedes equation

Question

I ve to create a pi approximation based on Archimedes equation. I ve to do so with for mode and recursive mode. In for mode i ve create sth like the above:

  double Pi_approximation(double r, double L){

   int i;
   double fin;
   double y;

   for(i=1; i<4; i++){

           y =sqrt(2*((r*r) - r*(sqrt(4*((r*r) - (L)))))); 

           L = y;
           printf("%f \n", L);
   }

   return y;
}

My problem is in second loop of for. In the first y is calculated normally but in second loop when i print y and L, it prints me their pointer!! Any idea?

Answer 1

It's hard to be sure what is happening, but I will take a guess anyway! Most likely the value you pass to one of the sqrt() calls is negative. When this happens, y (and hence L) will be NaN. The output then will be compiler dependent. For example on my compiler the output is:

-1.#IND00

Answer 2

you probably corrupted the code with memory leaks or similar in some other part... The code alone seems to work.