biot sarvat law

#include<cmath>
#include<iostream>
#include<cstdlib>

using namespace std;

struct point{
  double a;
  double b;
  double c;
};
float mag(point v);
double random_num(double a,double b);
point b_field_at_point(point p);
point unit(point v);

int main(){
  srand(332);
  double i;
  double j;
  double k;
  int boxsize=6;
  for(k=-boxsize;k<boxsize;k=k+1){
    for(i=-boxsize;i<boxsize;i=i+1){
      for(j=-boxsize;j<boxsize;j=j+1){
    point temp;
    point return_temp;
    temp.a=i;temp.b=j;temp.c=k;

    cout<<i<<" "<<j<<" "<<k<<" ";
    return_temp=b_field_at_point(temp);
    //cout<<sqrt(return_temp.a*return_temp.a+return_temp.b*return_temp.b+return_temp.c*return_temp.c)<<" ";
    if(mag(return_temp) <=1000){
      cout<<return_temp.a<<" "<<return_temp.b<<" "<<return_temp.c<<endl;
    }else{
      cout<<0<<" "<<0<<endl;};
      };
    };}
  return 0;}


double random_num(double a,double b){
  return (rand()/(double)RAND_MAX)*(b-a)+a;}

point b_field_at_point(point p){
  double radius=8;
  point I;
  I.a=I.b=I.c=0;

  double theta=0;
  double constants=0;
  //in amps
  double current=10000000;
  double i;
  double iterations=50000;

  for(i=0;i<iterations;i++){

    theta=random_num(0,2*3.14159265359);

    point dis_vect;
    point dl;
    dis_vect.a=p.a/*+(int)(random_num(-5,5))*/;
    dis_vect.b=p.b-radius*cos(theta);
    dis_vect.c=p.c-radius*sin(theta);

    constants=(4*3.14159265359*pow(10,-7)*current/(4*3.14159265359))*(1/(pow(mag(dis_vect),3)));



    //this is the cross product
    I.a=I.a+constants*(radius*sin(theta)*(p.c-radius*sin(theta))+radius*cos(theta)*(p.b-radius*cos(theta)));
    I.b=I.b+constants*(radius*p.a*cos(theta));
    I.c=I.c+constants*(-radius*p.a*sin(theta));

  }

  I.a=(2*3.141)*I.a/iterations;
  I.b=(2*3.141)*I.b/iterations;
  I.c=(2*3.141)*I.c/iterations;
  return I;

}

point unit(point v){

  point temp;
  double mag=sqrt(v.a*v.a+v.b*v.b+v.c*v.c);
  temp.a=v.a/mag;
  temp.b=v.b/mag;
  temp.c=v.c/mag;

  return temp;}

float mag(point v){

  return sqrt(v.a*v.a+v.b*v.b+v.c*v.c);}