#include <math.h>
#include <stdlib.h>
#include <string.h>

#ifdef _MSC_VER
#define EXPORT __declspec(dllexport)
#else
#define EXPORT
#endif

static const char *error = NULL;

double randn (double mu, double sigma)
{
  double U1, U2, W, mult;
  static double X1, X2;
  static int call = 0;
 
  if (call == 1)
    {
      call = !call;
      return (mu + sigma * (double) X2);
    }
 
  do
    {
      U1 = -1 + ((double) rand () / RAND_MAX) * 2;
      U2 = -1 + ((double) rand () / RAND_MAX) * 2;
      W = pow (U1, 2) + pow (U2, 2);
    }
  while (W >= 1 || W == 0);
 
  mult = sqrt ((-2 * log (W)) / W);
  X1 = U1 * mult;
  X2 = U2 * mult;
 
  call = !call;
 
  return (mu + sigma * (double) X1);
}


EXPORT int init(const char *str) 
{
  return 1;
}

EXPORT const char * getLastError() 
{
  return error;
}

EXPORT int eval(const char *func,
		int nArgs,
		const double **inReal,
		const double **inImag,
		int blockSize,
		double *outReal,
		double *outImag) 
{
  int i, j;


  
  if (strcmp("randgauss", func) == 0) 
    {
    if (nArgs != 3) 
      {
	error = "Expected 3 arguments (x (unused), mu,sigma)";
	return 0; 
      }
    for (i = 0; i < blockSize; i++) 
      {
	//double x = inReal[0][i];
	double mu=inReal[1][i];
	double sigma=inReal[2][i];
	//outReal[i] = (x == 0) ? 1 : sin(x) / x;
	outReal[i]=randn(mu,sigma);
      }
    return 1;
    }
  else 
    {
      error = "Unknown function";
      return 0;
    }
}