// RotationMatrix.cc
// Program to calculate coordinates after rotation

#include <iostream>
#include <cmath>
using namespace std;


void ComputeMatrix(float matrix[2][2], float angle);
void RotateCoordinates(float rot[2][2], float old[2], float transformed[2]);

int main()
{
   float angle, point[2], transformedPoint[2];
   float rotation[2][2];
		   
   // Get angle of rotation and initial position from input.
   cout << "Enter magnitude of rotation about z-axis in degrees: " ;
   cin >> angle;
   cout <<  "Input x and y coordinates: " << endl;
   cin >> point[0] >> point[1];

   // Calculate coefficients of rotation matrix and transform point.
   // The value of pi is declared in math.h as M_PI.
   ComputeMatrix(rotation, (M_PI*angle/180.0));
   RotateCoordinates(rotation, point, transformedPoint);

   // Output result.
   cout << "The coordinates in the rotated system (x,y) are ";
   cout << transformedPoint[0] << " and " << transformedPoint[1] << endl;
   return 0;
}

void ComputeMatrix(float matrix[2][2], float angle)
{
    matrix[0][0] = cos(angle);
    matrix[0][1] = sin(angle);
    matrix[1][0] = -sin(angle);
    matrix[1][1] = cos(angle);
}

void RotateCoordinates(float rot[2][2], float old[2], float transformed[2])
{
    transformed[0] = (rot[0][0] * old[0]) + (rot[0][1] * old[1]);
    transformed[1] = (rot[1][0] * old[0]) + (rot[1][1] * old[1]);
}