r22492 - /trunk/specific_analyses/relax_disp/disp_data.py -- March 17, 2014 - 14:30

Author: tlinnet
Date: Mon Mar 17 14:30:51 2014
New Revision: 22492

URL: http://svn.gna.org/viewcvs/relax?rev=22492&view=rev
Log:
Replaced funtion atan(omega1 / Delta_omega) with atan2(omega1 , Delta_omega), 
to make sure returned theta values are between 0 and pi.

This was done in the function return_offset_data() in the specific_analyses 
of relax_disp.
This was discussed in: 
http://thread.gmane.org/gmane.science.nmr.relax.devel/5210.

Modified:
    trunk/specific_analyses/relax_disp/disp_data.py

Modified: trunk/specific_analyses/relax_disp/disp_data.py
URL: 
http://svn.gna.org/viewcvs/relax/trunk/specific_analyses/relax_disp/disp_data.py?rev=22492&r1=22491&r2=22492&view=diff
==============================================================================
--- trunk/specific_analyses/relax_disp/disp_data.py     (original)
+++ trunk/specific_analyses/relax_disp/disp_data.py     Mon Mar 17 14:30:51 
2014
@@ -51,7 +51,7 @@
 """
 
 # Python module imports.
-from math import atan, floor, pi, sqrt
+from math import atan2, floor, pi, sqrt
 from numpy import array, float64, int32, ones, zeros
 from os.path import expanduser
 from random import gauss
@@ -2896,12 +2896,12 @@
                 if Delta_omega == 0.0:
                     theta[ei][si][mi][oi].append(pi / 2.0)
                 # Calculate the theta angle describing the tilted rotating 
frame relative to the laboratory.
+                # theta = atan(omega1 / Delta_omega).
                 # If Delta_omega is negative, there follow the symmetry of 
atan, that atan(-x) = - atan(x).
-                # Then it should be: theta = pi + atan(-x) = pi - atan(x) = 
pi - abs(atan( +/- x))
-                elif omega1 / Delta_omega > 0 :
-                    theta[ei][si][mi][oi].append(atan(omega1 / Delta_omega))
+                # Then it should be: theta = pi + atan(-x) = pi - atan(x) = 
pi - abs(atan( +/- x)).
+                # This is taken care of with the atan2(y, x) function, which 
return atan(y / x), in radians, and the result is between -pi and pi.
                 else:
-                    theta[ei][si][mi][oi].append(pi + atan(omega1 / 
Delta_omega))
+                    theta[ei][si][mi][oi].append(atan2(omega1 , Delta_omega))
 
                 # Calculate effective field in rotating frame
                 w_eff = sqrt( Delta_omega*Delta_omega + omega1*omega1 )