finding area of unit circle by monte carlo..

[niceguy]

Hi guys, I am attempting this, but cannot put finger on what is wrong. I have done it assuming a unit circle on origin and I thus use the positive quadrant and multiply the answer by 4.


Think maybe to do with the way I have generated random numbers.

Many thanks for your ideas..


insert

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



int main()

{
    
int N=100000,j;
double x1,x2,hit;

  
   x1=rand()/(double)RAND_MAX; //insuring random numbers between 0,1
   x2=rand()/(double)RAND_MAX;
   
   for(j=0;j<N;j++)   
   
       if(x1*x1+x2*x2<=1)
       
           {     
           hit++;
           }
    
    printf("volume: &#37;f", (4.0*hit)/N);  
    

    

system("pause");
exit(0);
}

[arpsmack]

You aren't generating the random numbers in your loop...
Oh you should probably initialize hit too...

[niceguy]

You aren't generating the random numbers in your loop...
Oh you should probably initialize hit too...

Ok i think i made the modifications...but still not right.


include

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

int main()

{
    
int N=100000,j;
double x1,x2,hit=0;

   srand(time(NULL));

  
   x1=rand()/(double)RAND_MAX;
   x2=rand()/(double)RAND_MAX;
   
   for(j=0;j<N;j++)   
   
       if(x1*x1+x2*x2<=1)
       
           {     
           hit++;
           }
    
    printf("volume: &#37;f\n", (4.0*hit)/N);  
    
system("pause");
exit(0);
}

[vart]

for(j=0;j<N;j++)   
{
   x1=rand()/(double)RAND_MAX;
   x2=rand()/(double)RAND_MAX;
   if(x1*x1+x2*x2<=1)
   {     
           hit++;
   }
}

[slingerland3g]

With Vart's code you may want to change your equation to:

printf("Area of circle: %f\n", 4.0 * (hit/N));

Guessing you are needing area and not volume? Area = r^2 *PI