CODEWITHSUNDEEP
c++mathreference
MrXQ
MrXQ

Reputation: 740

Converting from cartesian coordinates to polar coordinates and from polar to cartesian using reference

Im trying to make a simple converter using reference to convert between cartesian and polar the problem is it gives me wrong answers and sometimes 0 ,0 . I want to know what's the problem and how can i fix it . this is the code :

#include <iostream>
#include <cmath>
using namespace std;
void cartesianToPolar(int x,int y,float &r,float &q ) {
r = sqrt(x * x + y * y); q = atan(y / x);
}
void polarToCartesian(float r, float q, int &x, int &y) {
    x = r * cos(q); y = r * sin(q);
}
int main() {
    int cevap ;
    int  x = 0 , y = 0 ,xx = 0 , yy = 0;
    float r = 0 , q = 0 , rr = 0 , qq = 0 ;
    cout << "Choose please....." << endl;
    cout << "1-Cartesian -> polar "<<endl;
    cout << "2-polar ->Cartesian " << endl;
    cin >> cevap;
    if(cevap==1){
    cout << "enter x value: " ;
    cin >> x;
    cout << "enter y value: " ;
    cin >> y;
  
    cartesianToPolar(x,y,rr,qq);
    cout << "r:  " << rr << "        " << "Q: " << qq << endl;
    }
    else if (cevap==2)
    {
        cout << "enter r value : ";
        cin >> rr;
        cout << "enter Q value: ";
        cin >> qq;
        polarToCartesian(r, q, xx, yy);

        cout << "x: " << xx << "        " << "y: " << yy << endl;
    }
    return 0;
}

Upvotes: 0

Views: 4285

Answers (1)

atru
atru

Reputation: 4744

Results of both of your functions should be floats, not ints:

void cartesianToPolar(float x, float y, float &r, float &q ) {
    r = sqrt(x * x + y * y); q = atan(y / x);
}

void polarToCartesian(float r, float q, float &x, float &y) {
    x = r * cos(q); y = r * sin(q);
}

The values you were computing were correct, but the result was converted to integers afterwards. Conversion to int happens by trunctation, that is, 0.1 and 0.9 all become just 0.

You also had a typo in your polar to cartesian conversion in the main. Used the wrong variable. Correct is:

polarToCartesian(rr, qq, xx, yy);

Following @Yunnosch comment, you should use atan2() rather than atan(). Detailed explanation can be found here

Upvotes: 2

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