OpenEuphoria

arctan2

• Posted by Lucius Hilley <lhilley at CDC.NET> Mar 23, 1999
• 451 views

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Maybe the below derived information will help clear things up for you.
I tested the returned values to be sure I achieved the same results.
I used rand(255)-128 for X and Y to be sure I had both (+/-) values.
I also noticed his math multiplied by -1 more often than needed.

function arctan2(atom X, atom Y)
  sequence v
  v = repeat(0, 14)--Define space to show work.

  v[1]  = (Y = 0)
  v[8]  = (Y+v[1])
  v[10] = (X/v[8])

  v[2]  = (Y != 0)
  v[11] = arctan(v[10])*v[2]

  v[3]  = (Pi*.5)

  v[4]  = (Y < 0)

  v[5]  = (X >= 0)
  v[6]  = (X < 0)
  v[9]  = (v[6]-v[5])

  v[7]  = (-Pi*2)

  v[12] = v[3]*Sgn(X)*v[1]
  v[13] = Pi*v[4]*v[9]
  v[14] = v[7]*v[6]


  return abs(v[11]+v[12]-v[13]-v[14])
end function

        Lucius L. Hilley III

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