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#28647 needs_review defect

conversion of Symbolic Ring to FriCAS Expression Integer

Reported by:	mantepse	Owned by:
Priority:	major	Milestone:	sage-9.1
Component:	interfaces: optional	Keywords:	FriCAS
Cc:	chapoton	Merged in:
Authors:	Martin Rubey	Reviewers:
Report Upstream:	N/A	Work issues:
Branch:	u/mantepse/conversion_of_symbolic_ring_to_fricas_expression_integer (Commits)	Commit:	09bee2611190ef2d5071427ac69b6a8927e4fece
Dependencies:		Stopgaps:

Description (last modified by mantepse)

This ticket modifies the FriCAS interface so that symbolic ring elements are always converted to FriCAS Expression Integer or Expression Complex Integer, depending on whether the complex unit appears. Doing so, we fix the failure below.

see https://ask.sagemath.org/question/48431/why-this-integral-fail-using-fricas-algorithm/

for the original bug report:

integrate(sqrt(2)*x^2 + 2*x,x, algorithm="fricas")

Change History (17)

comment:1 Changed 3 months ago by mantepse

Branch set to u/mantepse/conversion_of_symbolic_ring_to_fricas_expression_integer

comment:2 Changed 3 months ago by mantepse

Authors set to Martin Rubey
Cc chapoton added
Commit set to 4c672a0d25b00b0f33c873a71164d5b6e6ac5916
Component changed from PLEASE CHANGE to interfaces: optional
Description modified (diff)
Status changed from new to needs_review
Type changed from PLEASE CHANGE to defect

New commits:

4c672a0 make sagemath SR convert to FriCAS EXPR INT

comment:3 follow-up: ↓ 4 Changed 3 months ago by tmonteil

Possible collision with #28641 which refers to the same ask.sagemath.org question.

comment:4 in reply to: ↑ 3 Changed 3 months ago by mantepse

Replying to tmonteil:

Possible collision with #28641 which refers to the same ask.sagemath.org question.

Yes, but the solutions are orthogonal to each other. In other words: after applying this branch, #28641 solves a different problem.

comment:5 Changed 3 months ago by chapoton

some failing doctests in src/sage/functions/generalized.py and src/sage/functions/exp_integral.py

comment:6 Changed 3 months ago by mantepse

There are unfortunately more problems. In particular, fricas(I) calls FriCASConverter.pyobject(I, I) (as it should). But this now returns I instead of %i.

comment:7 Changed 3 months ago by mantepse

I'm afraid my approach won't work, because FriCAS distinguishes between Expression Integer and Expression Complex Integer.

Put differently, the complex unit I is not an element of Expression Integer, but would have to be expressed as sqrt(-1). I see the following options:

rewrite I as sqrt(-1),
always use Expression Complex Integer,
detect whether I appears and distinguish accordingly,
somehow let FriCAS decide

I tend towards option 1., but I am not sure at all.

comment:8 Changed 3 months ago by mantepse

Status changed from needs_review to needs_work

help appreciated

comment:9 Changed 2 months ago by git

Commit changed from 4c672a0d25b00b0f33c873a71164d5b6e6ac5916 to 8948d3883678895a95fcc67f72801375e3f23832

Branch pushed to git repo; I updated commit sha1. New commits:

8948d38 try to fix conversion of complex expressions to fricas

comment:10 Changed 2 months ago by mantepse

Description modified (diff)
Status changed from needs_work to needs_review

comment:11 Changed 2 months ago by mantepse

Status changed from needs_review to needs_work

I think I have to make an exception for the conversion of symbols, because otherwise fricas.integrate(ex, x) won't work anymore.

comment:12 Changed 2 months ago by git

Commit changed from 8948d3883678895a95fcc67f72801375e3f23832 to d1b449088d9423f1f8faadd0d6e09a1ed873ca30

Branch pushed to git repo; I updated commit sha1. New commits:

8601700	`fix doctests`
4205759	`Merge branch 'u/mantepse/conversion_of_symbolic_ring_to_fricas_expression_integer' of git://trac.sagemath.org/sage into t/28647/conversion_of_symbolic_ring_to_fricas_expression_integer`
d1b4490	`Merge branch 'develop' into t/28647/conversion_of_symbolic_ring_to_fricas_expression_integer`