[yt-svn] commit/yt: ngoldbaum: Merged in xarthisius/yt (pull request #1766)

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1 new commit in yt:

https://bitbucket.org/yt_analysis/yt/commits/6de676ee8923/
Changeset:   6de676ee8923
Branch:      yt
User:        ngoldbaum
Date:        2015-10-05 21:03:53+00:00
Summary:     Merged in xarthisius/yt (pull request #1766)

[opt] Minor performance optimization for photon_simulator
Affected #:  1 file

diff -r 62d32295a0219e9859c64f1a8c6d0ff15a2bc385 -r 6de676ee8923b1bf55cb5990452646f2b09addb8 yt/analysis_modules/photon_simulator/photon_models.py
--- a/yt/analysis_modules/photon_simulator/photon_models.py
+++ b/yt/analysis_modules/photon_simulator/photon_models.py
@@ -199,15 +199,24 @@
                 ei = start_e
                 for cn, Z in zip(number_of_photons[ibegin:iend], metalZ[ibegin:iend]):
                     if cn == 0: continue
+                    # The rather verbose form of the few next statements is a
+                    # result of code optimization and shouldn't be changed
+                    # without checking for perfomance degradation. See
+                    # https://bitbucket.org/yt_analysis/yt/pull-requests/1766
+                    # for details.
                     if self.method == "invert_cdf":
-                        cumspec = cumspec_c + Z*cumspec_m
-                        cumspec /= cumspec[-1]
+                        cumspec = cumspec_c
+                        cumspec += Z * cumspec_m
+                        norm_factor = 1.0 / cumspec[-1]
+                        cumspec *= norm_factor
                         randvec = np.random.uniform(size=cn)
                         randvec.sort()
                         cell_e = np.interp(randvec, cumspec, ebins)
                     elif self.method == "accept_reject":
-                        tot_spec = cspec.d+Z*mspec.d
-                        tot_spec /= tot_spec.sum()
+                        tot_spec = cspec.d
+                        tot_spec += Z * mspec.d
+                        norm_factor = 1.0 / tot_spec.sum()
+                        tot_spec *= norm_factor
                         eidxs = np.random.choice(nchan, size=cn, p=tot_spec)
                         cell_e = emid[eidxs]
                     energies[ei:ei+cn] = cell_e

Repository URL: https://bitbucket.org/yt_analysis/yt/

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