#include <stdio.h>
#include <stdlib.h>

unsigned long seed=7;

void ansistandardsrand(unsigned int seed_set);
double ansistandardrand(long a, long c);

/*
  Exercise 1.5, see README

*/

main(int argc, char **argv)
{
  /* 
     This code assumes a mantissa in a double greater than the size of an int.
     If this is not true on your machine, you may end up in an infinite loop
  */

  int i;
  long a,c;
  double x,y;
  FILE *fp;

  ansistandardsrand(7);

  fp=fopen("ansixy_mod1.dat","w");
  for (i=0;i<10000;i++) {
    a=432764376; c=32132;
    x=ansistandardrand(a,c);
    y=ansistandardrand(a,c);
    fprintf(fp,"%.10g %.10g\n",x,y);
  }
  fclose(fp);

  fp=fopen("ansixy_mod2.dat","w");
  for (i=0;i<10000;i++) {
    a=436; c=322;
    x=ansistandardrand(a,c);
    y=ansistandardrand(a,c);
    fprintf(fp,"%.10g %.10g\n",x,y);
  }
  fclose(fp);

  fp=fopen("ansixy_mod3.dat","w");
  for (i=0;i<10000;i++) {
    a=100076; c=132672;
    x=ansistandardrand(a,c);
    y=ansistandardrand(a,c);
    fprintf(fp,"%.10g %.10g\n",x,y);
  }
  fclose(fp);

  fp=fopen("ansixy_mod4.dat","w");
  for (i=0;i<10000;i++) {
    a=4329984; c=13178;
    x=ansistandardrand(a,c);
    y=ansistandardrand(a,c);
    fprintf(fp,"%.10g %.10g\n",x,y);
  }
  fclose(fp);

  fp=fopen("ansixy_mod5.dat","w");
  for (i=0;i<10000;i++) {
    a=432109; c=1232178;
    x=ansistandardrand(a,c);
    y=ansistandardrand(a,c);
    fprintf(fp,"%.10g %.10g\n",x,y);
  }
  fclose(fp);

}

double ansistandardrand(long a, long c)
{
  /* Original:

  long a=1103515245;
  long c=12345;

  */

  long div=32768;

  seed = seed*a + c;
  return (double) ((seed/65536) % div)/div;
}

void ansistandardsrand(unsigned int seed_set)
{
  seed=seed_set;
}