Answer 4—Rectangular-to-polar conversion is a little trickier. You need a function, often called arg, which can convert two numbers representing a position on a 2-D plane into the angle it represents with respect to the positive x-axis in that plane. Arctangent by itself is insufficient because it wraps every 180°. arg produces answers that cover a full 360°, depending on the signs of both arguments.

Contributor: David Tweed