//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//This baby program prints your name and computes an L2-norm of your birthdate
// it also sets up a random vector and computes its average
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//%%% prototypes of standard functions and declarations first
#include <stdio.h>   // you need this for printing
#include <stdlib.h>  // you need this for rand()
#include <math.h>    // you need this for sqrt function
#include <malloc.h>  // you need this for allocations
//****************************************************
int main() 
{
#define MAXN 8
  const int n=MAXN;
  float     x[MAXN]; // this is static allocation, we'll use dynamic for xrand
  int nlarge;
  float *xrand;
  int i;
  char * myname[20];
  float norm;
  
  //%%% input and initialize variables
  // name
  printf ("Enter your name (20 characters, np spaces, you can use underscore):\n");
  scanf("%s",myname);
  printf("%s\n",myname);
  
  
  //%%% input your birthdate      
  printf("Enter %d digits of your birthdate separated by space or new line\n",n);
  for (i = 0; i<n; i++){
    int digit;
      scanf("%d",&digit);
      x[i]=(float)digit;
  }
  // echo the numbers of your birthdate
  for (i = 0;i<n;i++) printf("%g ",x[i]);   
  printf("\n");
  
  //%%% compute the L2 norm of the vector containing your birthdate 
  norm = 0.0;      
  for (i = 0;i<n;i++){
      float y = x[i];
      norm = norm + y*y;
  }
  norm = sqrt(norm);
  printf("Euclidean norm of your birthdate:%g\n", norm);

  // %%%%%%%%%%%%%%%%%
  // allocate memory for x and check if you got it
  printf("Enter large number to be the size of your random array:");
  scanf("%d",&nlarge);
  printf("Trying to allocate %d floats ... ",nlarge);
  xrand = (float *) malloc ( nlarge * sizeof(float) );
  if (xrand == NULL) {
    printf("Not enough memory"); return -1;
  } else {
    printf("Memory for the random vector allocated OK.\n");
  }

  for (i=0;i<nlarge;i++){
    int y = rand();    // this is a random integer
    //... below we cast it to a random float from (0,1)
    xrand [i] = ((float)y) / ( (float)(RAND_MAX) +1.0); 
  }
  printf("\n");

  float sum = 0.0;      
  for (i = 0; i<nlarge; i++){
    float y = xrand[i];
    sum = sum + y;
  

  printf("Sum of random vector of size:%d is %g average = %g\n", 
	 nlarge,sum,sum/nlarge);

}