[Scipy-tickets] [SciPy] #1758: add erfcx function (based on wofz)

SciPy Trac scipy-tickets@scipy....
Mon Oct 29 14:30:19 CDT 2012


#1758: add erfcx function (based on wofz)
-------------------------+--------------------------------------------------
 Reporter:  stevenj      |       Owner:  somebody   
     Type:  enhancement  |      Status:  new        
 Priority:  normal       |   Milestone:  Unscheduled
Component:  Other        |     Version:  devel      
 Keywords:               |  
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 It would probably be a good idea to add the scaled error function erfcx(x)
 = exp(x^2) erfc(x).  You can implement this trivially by using
 special.wofz, since erfcx(x) = wofz(ix).

 The advantage of providing it as erfcx is that many users are probably
 expecting it under that name [e.g. from Matlab
 http://www.mathworks.com/help/matlab/ref/erfcx.html], and may not realize
 the relationship to wofz.  Googling for "erfcx scipy" turns up several
 cases of people looking for this functionality.

 Note that the current wofz implementation (Faddeeva_w.cc) detects the case
 where its argument is purely imaginary and calls a specialized real-
 argument erfcx routine in that case.  So, there should be no significant
 performance penalty to implementing erfcx(x) via wofz even for real x.

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1758>
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