Symbolic products are currently broken.

[EmmanuelCharpentier]

The symbolic product is currently broken in Sage :

• It cannot be created in Sage :

sage: var("j,p", domain="integer")
sage: X,Y=function("X,Y")
sage: prod(X(j),j,1,p)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-5-85e69544cbe9> in <module>()
----> 1 prod(X(j),j,Integer(1),p)

/usr/local/sage-8/src/sage/misc/misc_c.pyx in sage.misc.misc_c.prod (/usr/local/sage-8/src/build/cythonized/sage/misc/misc_c.c:1596)()
     69 
     70 
---> 71 def prod(x, z=None, Py_ssize_t recursion_cutoff=5):
     72     """
     73     Return the product of the elements in the list x.

TypeError: prod() takes at most 3 positional arguments (4 given)
sage: product(X(j),j,1,p)
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-6-4d04d74c7489> in <module>()
----> 1 product(X(j),j,Integer(1),p)

NameError: name 'product' is not defined

• Creatnig it it by casting a Maxima expression via the library interface gives nonsense :

sage: X(j).maxima_methods().prod(j,1,p)
X(j)^p
sage: X(j).maxima_methods().product(j,1,p)
X(j)^p

(Note : similar nonsense also happens with sums :

sage: X(j).maxima_methods().sum(j,1,p)
p*X(j)

)

• But something (what ?) can be created via the Maxima pexpect interface :

sage: maxima("prod(X(j),j,1,p)").sage().log().log_expand()
sum(log(X(j)), j, 1, p)

The part of the problem bound to the Maxima library interface is the object of #22920. The present ticket aims at creating a Sage function/method correctly creating a symbolic product object.

CC: @rwst

Component: symbolics

Keywords: symbolics

Issue created by migration from https://trac.sagemath.org/ticket/22914

[rwst]

comment:2

Duplicate of #17505.

[EmmanuelCharpentier]

comment:3

Replying to @rwst:

Duplicate of #17505.

Wups ! You're right. I oversaw it (and #17502 and #20179) when consulting the symbolics page.

Curiosity : why setting the status to neeeds_review ?

[rwst]

comment:4

Replying to @EmmanuelCharpentier:

Curiosity : why setting the status to neeeds_review ?

I want you as the ticket reporter to agree. Could you please add your ticket description to #17505?

[EmmanuelCharpentier]

comment:5

Description pasted on #17505.

[embray]

comment:6

Closing tickets in the sage-duplicate/invalid/wontfix module with positive_review (i.e. someone has confirmed they should be closed).