Hi,
Le jeudi 30 avril 2015 17:44:39 UTC+2, Nils Bruin a écrit :
>
>
> This is probably just a nameclash, since pickling symbolic expressions.
> Pickling symbolic expressions rather directly depends on pynac's
> serialization, so we're restricted by the limitations that has.
>
Thanks for your answer. There is no predefined 'H' function in Sage, so do
you mean a nameclash with a predefined function 'H' in Pynac ? Which
function is it ? It seems to be (x,y) |--> - x ln(1-xy), but I don't see
why this function is special and would deserve a predefined name... In any
case, the symbolic function 'H' has to have two arguments (so it excludes
the Heaviside function), because with a single one or three of them, it is
OK. Changing the names of the arguments does not help:
loads(dumps(function('H', u, v))) still returns -u*log(-u*v + 1).
Note the following:
>
> sage: function('sin')(x).diff()
> D[0](sin)(x)
> sage: loads(dumps(function('sin')(x))).diff()
> cos(x)
>
> As you can see, pickling a fresh symbolic function that happens to clash
> with an existing one doesn't work properly.
>
Thanks for this example. It's clear that naming a fresh function 'sin' may
lead to some trouble. However, as mentionned above, I don't see the problem
with 'H' (nor 'G')...
Eric.
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