got a little bored and thought i would make something useless to most....to simply show my method
it handles 3 coord systems. sphere , rectangular and cylinder systems. //Three Dimension Coordinate Systems Converter
#include <iostream>
#include <math.h>
#include<cstring>
#include<cstdlib>

#define PI 3.1415926535897932384626433832795
#define FAC1 (180.0/PI)
#define FAC2 (PI/180.0)
using namespace std;

typedef struct
{
double d1;
double d2;
double d3;
string str;
string str1[2];
string str2[2];
string str3[2];
} Coordinate;

class convt
{
private:
Coordinate cr;//Cartesian (rectangular)
Coordinate cc;//Cylinderical
Coordinate cs;//Spherical
public:
convt(){
cr.str = "Cartesian coordinate system";
cc.str = "Cylindrical coordinate system";
cs.str = "Spherical coordinate system";
//Cartesian
cr.str1[0] = "x = ";
cr.str2[0] = "y = ";
cr.str3[0] = "z = ";
cr.str1[1] = " Unit";
cr.str2[1] = " Unit";
cr.str3[1] = " Unit\n";

//Cylindrical
cc.str1[0] = "Rho = ";
cc.str2[0] = "Phi = ";
cc.str3[0] = "z = ";
cc.str1[1] = " Unit";
cc.str2[1] = " Degree";
cc.str3[1] = " Unit\n";
//Spherical
cs.str1[0] = "R = ";
cs.str2[0] = "Theta = ";
cs.str3[0] = "Phi = ";
cs.str1[1] = " Unit";
cs.str2[1] = " Degree";
cs.str3[1] = " Degree\n";
}
void setVarr(double x,double y , double z){cr.d1 = x;cr.d2 = y; cr.d3 = z;}
void setVarc(double x,double y , double z){cc.d1 = x;cc.d2 = y; cc.d3 = z;}
void setVars(double x,double y , double z){cs.d1 = x;cs.d2 = y; cs.d3 = z;}


void convertr_c()
{
//convert from Cartesian to Cylindrical
cc.d1 = sqrtl(cr.d1*cr.d1 + cr.d2 * cr.d2);//Rho
cc.d2 = atan(cr.d2/cr.d1);//Phi
cc.d3 = cr.d3;//z
}
void convertc_s()
{
//Convert from cylinderical to spherical
cs.d1 = sqrtl(cc.d1 * cc.d1 + cc.d3 * cc.d3);//r
cs.d2 = atan(cc.d1/cc.d3);//theta
cs.d3 = atan((cc.d1 * sin(cc.d2)) /(cc.d1 * cos(cc.d2)));//phi
}
void converts_r()
{
//convert from spherical to cartesian
cr.d1 = cs.d1 * sin(cs.d2) * cos(cs.d3);
cr.d2 = cs.d1 * sin(cs.d2) * sin(cs.d3);
cr.d3 = cs.d1 * cos(cs.d2);
}
friend void disp(convt&);
};
void disp(convt &conv)
{
cout << endl << conv.cr.str << endl;//display rectangular
cout <<"-------------------------------\n";
cout << conv.cr.str1[0] << conv.cr.d1 << conv.cr.str1[1] << endl;
cout << conv.cr.str2[0] << conv.cr.d2 << conv.cr.str2[1] << endl;
cout << conv.cr.str3[0] << conv.cr.d3 << conv.cr.str3[1] << endl;

cout << conv.cc.str << endl;//display cylindrical
cout <<"-------------------------------\n";
cout << conv.cc.str1[0] << conv.cc.d1 << conv.cc.str1[1] << endl;
cout << conv.cc.str2[0] << FAC1 * conv.cc.d2 << conv.cc.str2[1] << endl;
cout << conv.cc.str3[0] << conv.cc.d3 << conv.cc.str3[1] << endl;

cout << conv.cs.str << endl;//display spherical
cout <<"-------------------------------\n";
cout << conv.cs.str1[0] << conv.cs.d1 << conv.cs.str1[1] << endl;
cout << conv.cs.str2[0] << FAC1 * conv.cs.d2 << conv.cs.str2[1] << endl;
cout << conv.cs.str3[0] << FAC1 * conv.cs.d3 << conv.cs.str3[1] << endl << endl;
}
int main()
{
convt con;
double dx1,dx2,dx3;
char ch;

for(;;)
{
cout << "\n3D Coordinate Converter" << endl;
cout << "\n\t1) Rectangular Coordinate System (x, y, z) " << endl;
cout << "\t2) Cylinderical Coordinate System (Rho, Phi, z)" << endl;
cout << "\t3) Spherical Coordinate System (R, Theta, Phi)" << endl;
cout << "\t4) Exit " << endl << endl;
cout << "Hint: The used angles are in degrees" << endl << endl;
cout << "Choose one option : ";
cin >> ch;

if(ch == '1' || ch == '2' || ch == '3' )
{
cout << "\nEnter coordinates of the chosen system:";
cout << "\nEnter 1st axis :";
cin >> dx1;
cout << "Enter 2nd axis :";
cin >> dx2;
cout << "Enter 3rd axis :";
cin >> dx3;
switch(ch)
{
case '1':
{
con.setVarr(dx1,dx2,dx3);
con.convertr_c();
con.convertc_s();
disp(con);
break;
}
case '2':
{
dx2 = dx2 * FAC2;
con.setVarc(dx1,dx2,dx3);
con.convertc_s();
con.converts_r();
disp(con);
break;
}
case '3':
{
dx2 = dx2 * FAC2;
dx3 = dx3 * FAC2;
con.setVars(dx1,dx2,dx3);
con.converts_r();
con.convertr_c();
disp(con);
break;
}
}
}
else if( ch == '4')
break;
else
cout << "Wrong number choosen. Try to choose right option :" << endl << endl;
}
return 0;
}