r23414 - /branches/disp_speed/lib/dispersion/cr72.py -- May 26, 2014 - 13:38

Author: tlinnet
Date: Mon May 26 13:38:09 2014
New Revision: 23414

URL: http://svn.gna.org/viewcvs/relax?rev=23414&view=rev
Log:
Critical fix for the math domain catching of model CR72.

This was discovered with the added 8 unit tests demonstrating edge case 'no 
Rex' failures.

This follows from the ideas in the post 
http://article.gmane.org/gmane.science.nmr.relax.devel/5858.
This is related to: task #7793: (https://gna.org/task/?7793) Speed-up of 
dispersion models.

This is to implement catching of math domain errors, before they occur.

When kex is large, ex: kex = 1e5, the values of:
etapos = eta_scale * sqrt(Psi + sqrt_psi2_zeta2) / cpmg_frqs

will exceed possible numerical representation.

The cathing of these occurences needed to be re-written.

Modified:
    branches/disp_speed/lib/dispersion/cr72.py

Modified: branches/disp_speed/lib/dispersion/cr72.py
URL: 
http://svn.gna.org/viewcvs/relax/branches/disp_speed/lib/dispersion/cr72.py?rev=23414&r1=23413&r2=23414&view=diff
==============================================================================
--- branches/disp_speed/lib/dispersion/cr72.py  (original)
+++ branches/disp_speed/lib/dispersion/cr72.py  Mon May 26 13:38:09 2014
@@ -128,9 +128,9 @@
     k_BA = pA * kex
     k_AB = pB * kex
 
-    # Catch parameter values that will result in no exchange, returning flat 
R2eff = R20 lines.
-    if dw == 0.0 or pA == 1.0 or kex == 0.0:
-        return array([r20_kex]*num_points)
+    # Catch parameter values that will result in no exchange, returning flat 
R2eff = R20 lines (when kex = 0.0, k_AB = 0.0).
+    if dw == 0.0 or pA == 1.0 or k_AB == 0.0 or kex >= 1.e5:
+        return array([r20a]*num_points)
 
     # The Psi and zeta values.
     if r20a != r20b:
@@ -156,16 +156,12 @@
     # Catch math domain error of cosh(val > 710).
     # This is when etapos > 710.
     if max(etapos) > 700:
-        R2eff = array([1e100]*num_points)
-
-        return R2eff
+        return array([r20a]*num_points)
 
     # The arccosh argument - catch invalid values.
     fact = Dpos * cosh(etapos) - Dneg * cos(etaneg)
     if min(fact) < 1.0:
-        R2eff = array([r20_kex]*num_points)
-
-        return R2eff
+        return array([r20_kex]*num_points)
 
     # Calculate R2eff.
     R2eff = r20_kex - cpmg_frqs * arccosh( fact )