/* 1次元ランダムウォーク */

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

main()
{
  unsigned int seed;
  int nran;
  int i,j;
  int istep,nstep;
  float a1;
  float h;
  float x;
  double step;

  FILE *output;
  
  output = fopen("ev.dat","w");

  printf("Input: seed \n");
  scanf("%u", &seed);
  printf("Input: Number of steps:\n");
  scanf("%u", &nstep);

  srand(seed);

  h=1.0;

  x=0.0;
  for(istep=0; istep < nstep; istep++){
    j=rand();
    a1=j/(RAND_MAX+1.0);
    if(a1<0.5)
      x=x-h;
    else
      x=x+h;
    
    printf("istep= %d,  x=%.5f\n",istep,x); 
    fprintf(output, "%d  %f\n",istep,x);
  }

  return;
}