Is theta = atan2(omega1, Delta_omega) of theta = atan2(Delta_omega, omega1) -- July 25, 2014 - 19:46

Hi Edward.

I was stumpling over the expression
theta = atan2(omega1, Delta_omega)

in:
specific_analyses/relax_disp/data.py in return_offset_data().

atan2 requires:
math.atan2(y, x)
Return atan(y / x), in radians. The result is between -pi and pi. The
vector in the plane from the origin to point (x, y) makes this angle
with the positive X axis. The point of atan2() is that the signs of
both inputs are known to it, so it can compute the correct quadrant
for the angle. For example, atan(1) and atan2(1, 1) are both pi/4, but
atan2(-1, -1) is -3*pi/4.

But what is y, and x?

If I look at my own figure at:
http://wiki.nmr-relax.com/images/1/12/Fig1_Palmer_Massi_2006.png

I would say that y is Delta_omega, and x is omega1.

Have I done this wrong earlier?

Best
Troels