Difference between revisions of "CPP/Math/Trig"

#include <cmath>
#include <iostream>
 
void TestAtan2();
 
int main()
{
  TestAtan2();
 
  double x1 = 0;
  double y1 = 0;
  double x2 = 100;
  double y2 = 100;
 
  std::cout << 180./3.14159 * atan((x2-x1)/(y2-y1)) << std::endl;
  return 0;
}
 
void TestAtan2()
{
  // syntax is atan2(y,x)
 
  std::cout << "right: " << atan2(0,1) << std::endl;
  std::cout << "up right: " << atan2(1,1) << std::endl;
  std::cout << "up: " << atan2(1,0) << std::endl;
  std::cout << "up left: " << atan2(1,-1) << std::endl;
  std::cout << "left: " << atan2(0,-1) << std::endl;
  std::cout << "down left: " << atan2(-1,-1) << std::endl;
  std::cout << "down: " << atan2(-1,0) << std::endl;
  std::cout << "down right: " << atan2(-1,1) << std::endl;
 
/* Output:
right: 0
up right: 0.785398
up: 1.5708
up left: 2.35619
left: 3.14159
down left: -2.35619
down: -1.5708
down right: -0.785398
*/
  // -pi is left (-x direction), then moving counter clockwise, it sweeps a full circle back to pi
}