atan2

atan2 y, x

• Returns the arctangent of y/x in the range -to A quick way to get an approximate value of is to say:
  
  

  $pi = atan2(1,1) * 4;
  

  
  
  For the tangent operation, you may use the POSIX::tan() function, or use the familiar relation:
  
  

  sub tan {
   sin($_[0]) / cos($_[0]) }