tan-1()

[Labdabeta]

What is the equivalent of tan-1(theta) [inverse tangent] in Java?

[JeffGrigg]

http://stackoverflow.com/questions/3449826/how-do-i-find-the-inverse-tangent-of-a-line

[Labdabeta]

That thread asked the exact question I need an answer to actually and that atan2 function looks promising. But I cant get it to work. Here is a better question for my needs: I have two points, (x1,y1) and (x2,y2) and I need to get their angle in degrees clockwise from pure "North". How do I do this?

[Taywin]

If I remember correctly, atan() takes radiant value, not degree. The atan2() takes the diff of y and diff of x (y2-y1, x2-x1).

[JamesCherrill]

Taywin's right - the Math trig functions work in radians, not degrees (2*Pi radians = 360 degrees). Also I think zero angle is pure "East" (is along the x axis), not North.

[JamesCherrill]

... and I think the angles increase anti-clockwize as well

[Labdabeta]

Thanks.