Opened 6 years ago

Last modified 5 years ago

#18832 closed defect

non-numeric non-symbolic BuiltinFunction arguments — at Version 2

Reported by: rws Owned by:
Priority: major Milestone: sage-duplicate/invalid/wontfix
Component: symbolics Keywords:
Cc: jdemeyer Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
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Description (last modified by rws)

Symbolic expressions can be seen as programs for applying functions to numerics and symbolics. Non-numeric non-symbolics (NNNS, most of the rest of Sage) are usually not handled by symbolic functions, although they often allow the same operations and many of the functions. The manual workaround is to evaluate the expression "on x" and then to substitute x with the respective NNNS. We propose that BuiltinFunction automates this process.

Part of this is already duplicated in rings.arith but the need arises with symbolic functions returning polynomials, e.g. #16813. At the moment BuiltinFunction simply converts the NNNS argument, losing the type information.

Practically, BuiltinFunction should eval with x, try substitution, and throw an error if the substitution leads to unknown methods of the NNNS. I.e.

sage: elliptic_f (x, 1)
log(tan(1/4*pi + 1/2*x))
sage: elliptic_f (polygen(CC), 1)
AttributeError: cannot apply function to argument x: argument does not know how to do log
(coming from this exception)
AttributeError: 'Polynomial_generic_dense_field' object has no attribute 'log'

Change History (2)

comment:1 Changed 6 years ago by rws

  • Description modified (diff)

comment:2 Changed 6 years ago by rws

  • Description modified (diff)
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