Re: laguerre.m functions in specfun package

[Juan Pablo Carbajal]

On Wed, Apr 29, 2015 at 3:58 PM, Colin Macdonald
<address@hidden> wrote:
> On 29/04/15 06:46, Juan Pablo Carbajal wrote:
>>
>> On Tue, Apr 28, 2015 at 6:30 PM, Carnë Draug <address@hidden>
>> wrote:
>>>
>>> I am arguing that dirac and heaviside should be moved to the symbolic
>>> package.  And then we drop the specfun package.
>>> See https://savannah.gnu.org/patch/?8644#comment13
>>>
>>
>> I completely disagree with this.
>> Symbolic does not offer replacement for these functions. Specially it
>> is not true that
>>
>> multinom, multinom_coeff, multinom_exp -- I think these are monomials,
>> and nthcoeff in the sym,bolic package
>>
>> (mind the "I think"). These functions are optimized for numeric not
>> for symbolic manipulation (which by the way is the main role of
>> octave). The symbolic version of these function will just ad an over
>> heard in time execution and memory!
>>
>> Please always think of this when you want to replace a numerical
>> version of a function with a symbolic one (please!). You should
>> provide performance (time and memory) justifying the change.
>
>
> I develop Symbolic but I have no particular agenda here either way: so long
> as I can rely on users having some of these functions for doubles.
>
> re: performance: *generally speaking* function with symbolic arguments call
> e.g., "@sym/dirac.m", whereas with double arrays they call e.g.,
> "@double/dirac.m" so there should be no cpu/mem performance penalty for
> numerical computing.  I'm keen to ensure it stays that way.
>
>
>> In any case, if you want to get rid of specfun (I do not know why you
>> would want that!), I would say be mindful if your are not a user of
>> the package. Your interest might not coincide with the interest of the
>> true/intended users.

So in the particular case of multinom. What would be the code to
evaluate a 100x5 matrix representing 100 values on 5 terms of a
multinomial: (x1 + x2 + x3 + x4 + x5)^3
and get ans an answer all the terms of the expansion evaluate on the
100 input values?