Why Is My Pi Estimation Code Producing Incorrect Results?

[vladittude0583]

Here is what I have coded so far:

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

int randomNumber(void); // Function prototype for random number generator
void srand(unsigned int seed); // Function prototype for seeding the RNG

int main()
{
// Declaration of double variables

double x; // coordinate of dart
double y; // coordinate of dart
double v; // coordinate of dart
double estimatedPi;
double Pi;

// Declaration of long variables

long startValue;
long seed;
long impact;
long target;

// Declaration of initialization values

startValue = 100;
seed = time(NULL);
impact = 0;
target = 0;
Pi = 3.14159265358979;

srand(seed);

printf("\t\t\tPi Dart Simulator v1.2 \n\n");
printf("True Pi to 8 decimal places: 3.14159265358979 \n");
printf("Random number seed: 1225850161 \n\n");

printf(" Throws Hits Esimated Pi %%Error \n");
printf("====================================================\n\n");

while (impact < startValue && impact < 10000000)
{
x = (double)rand()/RAND_MAX;
y = (double)rand()/RAND_MAX;
impact += 1;

if ((sqrt(x*x + y*y)) <= 1.00)
{
target += 1;
estimatedPi = ((double)target / (double)impact)*4;
}

while (impact >= startValue)
{
printf("%10d %10d %10d %10d %10d \n", impact, target, estimatedPi,
(((estimatedPi) - Pi) / Pi)*100);
startValue *= 10;
impact = target = 0;
}
}

system("pause");
return 0;
}

unsigned long random = 1;

void srand(unsigned int seed)
{
random = seed;
}

int randomNumber()
{
random = random * 1103515245 + 12345;
return (unsigned int)(random / 65536) % 327768;
}


What I cannot figure out is why my values for the estimation of Pi and percent error is coming out wrong - PLEASE HELP

 

[zyh]

I tested your code, and there are many errors. I'm very curious whether it could compile on your system. Which compiler did you use?　
from the

system("pause");

, I guess that you are using Microsoft windows., and I'm not sure a it is a legal statement in gcc under linux.

int randomNumber(void); // Function prototype for random number generator

What does this function use for?

void srand(unsigned int seed); // Function prototype for seeding the RNG

srand() is a function supplied by standard c library. So, you needn't implement it yourself.

printf("%10d %10d %10d %10d %10d \n", impact, target, estimatedPi,
(((estimatedPi) - Pi) / Pi)*100);

You have Five "%", but you have only four associated parameters. And there is a mismatch of types. Because " estimatedPi " is declared as a double format variable, you should use "%lf" instead. So as the expression "(((estimatedPi) - Pi) / Pi)*100)".

After modifying the whole bugs, it works.
Here is the result in my system

Pi Dart Simulator v1.2

True Pi to 8 decimal places: 3.14159265358979
Random number seed: 1225850161

 Throws Hits Esimated Pi %Error
========================================== ==========

       100         78   3.120000  -0.687316
      1000        811   3.244000   3.259727
     10000       7793   3.117512  -0.766519
    100000      78629   3.145191   0.114553
   1000000     785078   3.140312  -0.040764
  10000000    7852331   3.140933  -0.021007

 

[piercas]

I would first like to commend you for your efforts in coding and attempting to simulate the estimation of Pi through darts. It is clear that you have put a lot of thought and effort into this project.

Upon reviewing your code, I can see that you have correctly declared and initialized your variables. However, there are a few areas where you may have made some errors.

Firstly, in your randomNumber() function, you are using an unsigned long variable to store the random number. However, in your main() function, you are casting this variable to a double when generating the coordinates for the darts. This may result in loss of precision and affect the accuracy of your estimation.

Additionally, in your while loop, you are incrementing the impact variable before checking if the dart has hit the target. This may result in a higher number of impacts than actual hits, leading to an inaccurate estimation of Pi.

Furthermore, in your printf statement, you are using the incorrect variable for the estimated Pi value. You are using "estimatedPi" instead of "estimatedPi" which may also lead to incorrect values being displayed.

To improve the accuracy of your simulation, I would suggest reviewing your code and making the necessary corrections to ensure the correct data types are used and variables are incremented and displayed accurately.

Lastly, I would also recommend including comments in your code to make it easier for others to understand and debug any errors.

I hope this helps and good luck with your project!