#2235 atan2() needs documentation tweak

[Ivar Christopher]

In the documentation for the atan2() function (included below), there is a good discussion about different orderings of x and y in different implementations, but there is no explicit definition of what x and y actually are. My first assumption is usually that the function returns the value of atan(x/y), but I've seen implementations where it is atan(y/x). This needs to be clearly stated.

public static QDataSet atan2(QDataSet y,
QDataSet x)

element-wise atan2, 4-quadrant atan. Note different languages have different argument order. Microsoft office uses atan2(x,y); IDL uses atan(y,x); Matlab uses atan2(y,x); and NumPy uses arctan2(y,x).

Parameters:
y - the y values
x - the x values
Returns:
angles between -PI and PI

[Jeremy Faden]

I've copied over a couple of sentences from the Java Math documentation. Please close this ticket of you agree this is sufficient.