Hi Troels,
There is another bug here. Although it looks like you are dividing by
zero when kex is 0.0, what is happening is that you have 0.0 / 0.0 !
The result should not be Inf (or a big number). Do you have access to
symbolic maths software such as Maxima, Mathematica, etc.? You should
put in the dispersion equations, and then ask the software to simplify
the equation with the assumption that kex = 0.0. Then you'll see that
the LM63 model collapses down to:
R2eff = R20.
You can also do this by hand. You'll see that tanh(0.0) = 0.0, and
phi_ex has kex in it so it too is 0.0. You can then just replace the
0.0 / 0.0 parts with 1:
R2eff = R20 + 0.0/0.0 (1 - 0.0/0.0),
R2eff = R20 + 1 (1 - 1),
R2eff = R20.
The 0.0 / 0.0 operation is the origin of the numpy warnings. The unit
tests I mentioned at
http://www.mail-archive.com/relax-devel@xxxxxxx/msg05742.html would
comprehensively catch all problems in the dispersion code.
Regards,
Edward
On 21 May 2014 13:03, <tlinnet@xxxxxxxxxxxxx> wrote:
Author: tlinnet
Date: Wed May 21 13:02:59 2014
New Revision: 23298
URL: http://svn.gna.org/viewcvs/relax?rev=23298&view=rev
Log:
Align math-domain catching for model LM63 with trunk implementation.
task #7793: (https://gna.org/task/?7793) Speed-up of dispersion models.
This is to implement catching of math domain errors, before they occur.
The catching of errors have to be more careful.
Modified:
branches/disp_speed/lib/dispersion/lm63.py
Modified: branches/disp_speed/lib/dispersion/lm63.py
URL:
http://svn.gna.org/viewcvs/relax/branches/disp_speed/lib/dispersion/lm63.py?rev=23298&r1=23297&r2=23298&view=diff
==============================================================================
--- branches/disp_speed/lib/dispersion/lm63.py (original)
+++ branches/disp_speed/lib/dispersion/lm63.py Wed May 21 13:02:59 2014
@@ -85,6 +85,15 @@
@type num_points: int
"""
+ # Catch divide with zeros (to avoid pointless mathematical operations).
+ if kex == 0.0:
+ return array([1e100]*num_points)
+
+ # Catch zeros (to avoid pointless mathematical operations).
+ # This will result in no exchange, returning flat lines.
+ if phi_ex == 0.0:
+ return array([r20]*num_points)
+
# Repetitive calculations (to speed up calculations).
rex = phi_ex / kex
kex_4 = 4.0 / kex
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Re: r23298 - /branches/disp_speed/lib/dispersion/lm63.py