C code for Von Neumann Middle Square

C codes

First we write a C code to get one random number using Von Neumann method

We choose a random number of desired digit using rand() and then apply Von Neumann method.

Then just by some changes we get a code for generating any number of random numbers.

The codes are as follows:

Code for generating one random number:


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

/*Von Neumann Algorithm*/
/*Programmers: Gursharn, Smruti, Shwetab, Sagnika, Kaustav*/
/*Date: Aug 14, 2010*/

unsigned long int randm(int n);
unsigned long int von(unsigned long int x, int n);

int main(void)
{
  unsigned long int x, s;
  int n;
  printf("Enter the number of digits in the seed value ");
  scanf("%d",&n);
  if (n >= 10){
    printf("TOO LARGE!!");
    exit(0);
  }
  x = randm(n);
  printf("\nRandom Number generated: %lu\n",von(x,n));
  return 0;
}


/*Generating Random Number of desired digit*/

unsigned long int randm(int n)
{
  double x;
  unsigned long int y;
  srand(getpid());
  x = rand()/(double)RAND_MAX;
  y =(int) (x * pow(10.0,(double) n));
  return y;
}


/*Calculating Random Number By Von Neumann method*/

unsigned long int von(unsigned long int x, int n)
{
  unsigned long int y;
  int k;
  k = n/2;
  y = (int)((x/pow(10.0, k * 1.0)) * x);
  y = y % (int) (pow(10.0, n * 1.0));
  return y;
}

Code for generating sequence of random number:


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

/*Von Neumann Algorithm To Generate Several Random Numbers*/
/*Programmers: Gursharn, Smruti, Shwetab, Sagnika, Kaustav*/
/*Date: Aug 14, 2010*/

unsigned long long int randm(int n);
unsigned long long int von(unsigned long long int x, int n);

int main(void)
{
  unsigned long long int x, s;
  int n, i, r;

  printf("Enter the number of digits in the seed value ");
  scanf("%d",&n);
  
  printf("Enter the total number of random numbers to be generated "); 
  scanf("%d",&r);

  if (n >=12){
    printf("TOO LARGE!!");
    exit(0);
  }
  
  x = randm(n);
  for(i = 0; i < r; i++){	
     s = von(x,n);
     x = s;
  printf("\nRandom Number generated: %lld\n",s);
  }
  return 0;
}


/*Generating Random Number of desired digit*/

unsigned long long int randm(int n)
{
  double x;
  unsigned long long int y;
  srand(getpid());
  x = rand()/(double)RAND_MAX;
  y =(unsigned long long int) (x * pow(10.0, n*1.0));
  return y;
}


/*Calculating Random Number By Von Neumann method*/

unsigned long long int von(unsigned long long int x, int n)
{
  unsigned long long int y;
  int k;
  k = n/2;
  y =(unsigned long long int)((x/pow(10.0, k * 1.0)) * x) % (unsigned long long int) (pow(10.0, n * 1.0));
  return y;
}

R Codes for Von Neuman Middle Square

First we select a random number of desired digit using runif().

Using this as a seed value we generate a sequence of random numbers.

The digits of these numbers are seperated out and then their relative frequencies are plotted.



#von neumann algorithm

von <- function(n){
  m <- floor(runif(1) * 10^n)
  k <- m * m
  i <- floor(n/2)
  t <- (k %/% (10^i)) %% (10^n)
  t
}


digit.sep <- function(x){
  n = nchar(x)
  x <- as.numeric(x)
  y <- rep(0, n)
  for(i in 1: n)
    y[i] = (x %/% (10 ^(n-i))) - 10* (x %/% (10^(n-i+1) )) 
  y
}

plot.von <- function(n){
  x <- matrix(0, nrow= n, ncol = 5)
  for(i in 1:n){
    t <- von(5)
    x[i, (6 - nchar(t)):5] <- digit.sep(t)
  }
  a <- rep(0,10)
  
  for(i in 1:10)
    a[i] = sum(x == (i-1))
  a = a/(n * 5)
  barplot(a, xlab = "digits", ylab = "Relative Frequency")
}