[Numpy-discussion] Proposal for changing the names of inverse trigonometrical/hyperbolic functions

Eric Firing efiring@hawaii....
Mon Nov 24 13:31:28 CST 2008

Francesc Alted wrote:
> Hi,
> After dealing with another issue, I realized that the names of inverse 
> trigonometrical/hyperbolic functions in NumPy don't follow the main 
> standards in computer science.  For example, where Python writes:
> asin, acos, atan, asinh, acosh, atanh
> NumPy choose:
> arcsin, arccos, arctan, arcsinh, arccosh, arctanh
> And not only Python, the former also seems to be the standard in 
> computer science.  Quoting:
> http://en.wikipedia.org/wiki/Inverse_hyperbolic_function
> """
> The usual abbreviations for them in mathematics are arsinh, arcsinh (in 
> the USA) or asinh (in computer science).
> ...
> The acronyms arcsinh, arccosh etc. are commonly used, even though they 
> are misnomers, since the prefix arc is the abbreviation for arcus, 
> while the prefix ar stands for area.
> """
> So, IMHO, I think it would be better to rename the inverse trigonometric 
> functions from ``arc*`` to ``a*`` prefix.  Of course, in order to do 
> that correctly, one should add the new names and add a 
> ``DeprecationWarning`` informing that people should start to use the 
> new names.  After two or three NumPy versions, the old function names 
> can be removed safely.
> What people think?

I have stumbled over this myself.  If there is resistance to removing 
the old names, then just leave them as synonyms; but definitely numpy 
should have asin etc.


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