
#include "stdlib.h"
#include "stdio.h"
#include "math.h"
#include "mex.h"

/*------Constants for rnd_uni()--------------------------------------------*/

#define IM1 2147483563
#define IM2 2147483399
#define AM (1.0/IM1)
#define IMM1 (IM1-1)
#define IA1 40014
#define IA2 40692
#define IQ1 53668
#define IQ2 52774
#define IR1 12211
#define IR2 3791
#define NTAB 32
#define NDIV (1+IMM1/NTAB)
#define EPS 1.2e-7
#define RNMX (1.0-EPS)

double rnd_uni(long *idum)
{
  long j;
  long k;
  static long idum2=123456789;
  static long iy=0;
  static long iv[NTAB];
  double temp;

  if (*idum <= 0)
  {
    if (-(*idum) < 1) *idum=1;
    else *idum = -(*idum);
    idum2=(*idum);
    for (j=NTAB+7;j>=0;j--)
    {
      k=(*idum)/IQ1;
      *idum=IA1*(*idum-k*IQ1)-k*IR1;
      if (*idum < 0) *idum += IM1;
      if (j < NTAB) iv[j] = *idum;
    }
    iy=iv[0];
  }
  k=(*idum)/IQ1;
  *idum=IA1*(*idum-k*IQ1)-k*IR1;
  if (*idum < 0) *idum += IM1;
  k=idum2/IQ2;
  idum2=IA2*(idum2-k*IQ2)-k*IR2;
  if (idum2 < 0) idum2 += IM2;
  j=iy/NDIV;
  iy=iv[j]-idum2;
  iv[j] = *idum;
  if (iy < 1) iy += IMM1;
  if ((temp=AM*iy) > RNMX) return RNMX;
  else return temp;

}/*------End of rnd_uni()--------------------------*/

void mexFunction(int nlhs, mxArray *plhs[],
                 int nrhs, const mxArray *prhs[])
{
  /* check to make sure the first input argument is a scalar */
  if( !mxIsDouble(prhs[0]) || mxIsComplex(prhs[0]) ||
      mxGetN(prhs[0])*mxGetM(prhs[0])!=1 ) {
    mexErrMsgTxt("Input x must be a scalar.");
  }
  
  double *seed = mxGetPr(prhs[0]);
  
  long lseed = (long)floor(*seed);
  
  double r = rnd_uni(&lseed);
  plhs[0] = mxCreateDoubleMatrix(1,1, mxREAL);
  *(mxGetPr(plhs[0])) = r;
  printf("input seed %f, %, output random %f\n", lseed, r);
  
}