integrate(..., algorithm="giac"): Incorrect conversion to Sage #28913

EmmanuelCharpentier · 2019-12-26T18:01:18Z

sage: Ex=(1-2*x^(1/3))^(3/4)/x
sage: integrate(Ex, x, algorithm="giac")
---------------------------------------------------------------------------
SyntaxError                               Traceback (most recent call last)
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/interfaces/giac.py in _sage_(self, locals)
   1100                 return symbolic_expression_from_string(result, lsymbols,
-> 1101                     accept_sequence=True)
   1102 

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/calculus/calculus.py in symbolic_expression_from_string(s, syms, accept_sequence)
   2384             _augmented_syms = syms
-> 2385             return parse_func(s)
   2386         finally:

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/misc/parser.pyx in sage.misc.parser.Parser.parse_sequence (build/cythonized/sage/misc/parser.c:5479)()
    538 
--> 539     cpdef parse_sequence(self, s):
    540         """

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/misc/parser.pyx in sage.misc.parser.Parser.parse_sequence (build/cythonized/sage/misc/parser.c:5369)()
    556         if tokens.next() != EOS:
--> 557             self.parse_error(tokens)
    558         if len(all) == 1 and isinstance(all, list):

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/misc/parser.pyx in sage.misc.parser.Parser.parse_error (build/cythonized/sage/misc/parser.c:9742)()
   1007     cdef parse_error(self, Tokenizer tokens, msg="Malformed expression"):
-> 1008         raise SyntaxError(msg, tokens.s, tokens.pos)
   1009 

SyntaxError: Malformed expression

During handling of the above exception, another exception occurred:

NotImplementedError                       Traceback (most recent call last)
<ipython-input-22-617e71e52902> in <module>()
----> 1 integrate(Ex, x, algorithm="giac")

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/misc/functional.py in integral(x, *args, **kwds)
    751     """
    752     if hasattr(x, 'integral'):
--> 753         return x.integral(*args, **kwds)
    754     else:
    755         from sage.symbolic.ring import SR

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression.integral (build/cythonized/sage/symbolic/expression.cpp:64575)()
  12389                     R = ring.SR
  12390             return R(integral(f, v, a, b, **kwds))
> 12391         return integral(self, *args, **kwds)
  12392 
  12393     integrate = integral

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/symbolic/integration/integral.py in integrate(expression, v, a, b, algorithm, hold)
    925         if not integrator:
    926             raise ValueError("Unknown algorithm: %s" % algorithm)
--> 927         return integrator(expression, v, a, b)
    928     if a is None:
    929         return indefinite_integral(expression, v, hold=hold)

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/symbolic/integration/external.py in giac_integrator(expression, v, a, b)
    430         return expression.integrate(v, a, b, hold=True)
    431     else:
--> 432         return result._sage_()

/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/interfaces/giac.py in _sage_(self, locals)
   1102 
   1103             except Exception:
-> 1104                 raise NotImplementedError("Unable to parse Giac output: %s" % result)
   1105         else:
   1106             return [entry.sage() for entry in self]

NotImplementedError: Unable to parse Giac output: Evaluation time: 2.82
12*(1/4*ln(abs((-2*x^(1/3)+1)^(1/4)-1))-1/4*ln((-2*x^(1/3)+1)^(1/4)+1)+1/2*atan((-2*x^(1/3)+1)^(1/4))+1/3*((-2*x^(1/3)+1)^(1/4))^3)

However, the following workaround works:

sage: from giacpy_sage import *
// Giac share root-directory:/usr/local/sage-P3-2/local/share/giac/
// Giac share root-directory:/usr/local/sage-P3-2/local/share/giac/
Help file /usr/local/sage-P3-2/local/share/giac/doc/fr/aide_cas not found
Added 0 synonyms
sage: libgiac.integrate(Ex,x).sage()
4*(-2*x^(1/3) + 1)^(3/4) + 6*arctan((-2*x^(1/3) + 1)^(1/4)) - 3*log((-2*x^(1/3) + 1)^(1/4) + 1) + 3*log(abs((-2*x^(1/3) + 1)^(1/4) - 1))

This seems to point to the (unwelcome) timing information added by Giac before its results... It's probably more of a booboo than a (real|hard) bug, but might defeat a whole problem if this error is raised before other algorithms has had a chance to report their results.

I'm not sure that this should be reported upstream (it should if there is no way to cleanly suppress the timing information).

Ccing the participants to #27958, which introduced this particular wolf in the general Sage integration sheepshed...

CC: @fchapoton @mwageringel @sagetrac-jakobkroeker @kcrisman @pjbruin @rwst @seblabbe @slel @sagetrac-tmonteil @videlec @vinklein @zimmermann6 @mforets @mezzarobba

Component: calculus

Keywords: symbolics giac integration

Author: Frédéric Chapoton

Branch: 297033a

Reviewer: Thierry Monteil

Issue created by migration from https://trac.sagemath.org/ticket/28913

The text was updated successfully, but these errors were encountered:

EmmanuelCharpentier · 2019-12-26T18:02:38Z

comment:1

Forgot Frederic Chapoton in the Cc list...

EmmanuelCharpentier · 2019-12-26T18:16:34Z

Changed keywords from none to symbolics giac integration

mwageringel · 2019-12-27T12:40:29Z

comment:3

I think it would make sense to use giacpy_sage for this in general, rather than the pexpect interface. Perhaps giacpy_sage could be turned into a standard package.

slel · 2019-12-28T06:29:56Z

comment:4

Replying to @mwageringel:

I think it would make sense to use giacpy_sage for this in general, rather than the pexpect interface. Perhaps giacpy_sage could be turned into a standard package.

I opened #28918 for that. See also #16688.

embray · 2020-01-06T14:10:03Z

comment:5

Ticket retargeted after milestone closed

seblabbe · 2020-04-21T12:20:28Z

comment:6

Is the following

sage: integrate(sqrt(x + sqrt(x)), x, algorithm='giac')

an other instance of the problem described in this ticket? See https://ask.sagemath.org/question/50885/is-there-a-way-to-integrate-sqrtxsqrtx-in-sage/

The result is:

Traceback (most recent call last):
...
AttributeError: 
...
During handling of the above exception, another exception occurred:
...
RuntimeError: An error occurred running a Giac command:
INPUT:
sage2
OUTPUT:
Warning, choosing root of [1,0,0,%%%{4,[1]%%%},%%%{4,[2]%%%}+%%%{-1,[1]%%%}] at parameters values [-97]
Warning, need to choose a branch for the root of a polynomial with parameters. This might be wrong.
The choice was done assuming [x]=[9]
Warning, need to choose a branch for the root of a polynomial with parameters. This might be wrong.
The choice was done assuming [x]=[54]
  ***   bug in PARI/GP (Bus Error), please report.sym2poly exception caught Error in PARI subsystem Error: Bad Argument Value
Warning, need to choose a branch for the root of a polynomial with parameters. This might be wrong.
The choice was done assuming [x]=[64]

  ***   bug in PARI/GP (Segmentation Fault), please report.sym2poly exception caught Error in PARI subsystem Error: Bad Argument Value

  ***   bug in PARI/GP (Segmentation Fault), please report.sym2poly exception caught Error in PARI subsystem Error: Bad Argument Value

  ***   Warning: normalizing a polynomial with 0 leading term.
  ***   Warning: normalizing a polynomial with 0 leading term.
Warning, choosing root of [1,0,0,%%%{4,[1]%%%},%%%{4,[2]%%%}+%%%{-1,[1]%%%}] at parameters values [6.38357630698]
  ***   Warning: normalizing a polynomial with 0 leading term.
  ***   Warning: normalizing a polynomial with 0 leading term.
Warning, choosing root of [1,0,0,%%%{4,[1]%%%},%%%{4,[2]%%%}+%%%{-1,[1]%%%}] at parameters values [82.1195442914]
2*(2*((1/6*sqrt(x)+1/24)*sqrt(x)-1/16)*sqrt(x+sqrt(x))-1/16*ln(sqrt(4*sqrt(x)+1-4*sqrt(x)*cos((pi*sign(im(sqrt(x)))*sign(x+re(sqrt(x)))-pi*sign(im(sqrt(x)))-2*atan(im(sqrt(x))/(x+re(sqrt(x)))))/2)+rootof([[-4,-4,0],[1,0,0,4*x,4*x^2-x]])*cos(1/2*(atan(im(sqrt(x))/(x+re(sqrt(x))))+(1-sign(x+re(sqrt(x))))*sign(im(sqrt(x)))*pi/2)))))

fchapoton · 2020-05-16T11:09:36Z

Branch: u/chapoton/28913

fchapoton · 2020-05-16T11:09:36Z

comment:8

here is a bandaid. A better would be to go through #28918

New commits:

`203f9eb`	`bandaid for giac pexpect unwanted timing display`

fchapoton · 2020-05-16T11:09:36Z

Commit: 203f9eb

fchapoton · 2020-05-16T11:09:36Z

Author: Frédéric Chapoton

fchapoton · 2020-05-16T17:24:42Z

comment:9

green bot, please review

sagetrac-tmonteil · 2020-05-16T18:59:18Z

comment:10

The fix looks good. How wbout adding a direct doctest in SAGE_ROOT/src/sage/symbolic/integration/integral.py pointing to this ticket ?

sagetrac-git · 2020-05-17T05:54:50Z

Changed commit from 203f9eb to 297033a

sagetrac-git · 2020-05-17T05:54:50Z

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

`297033a`	`trac 28913 adding yet another doctest`

fchapoton · 2020-05-17T05:56:06Z

comment:12

Doctest ajouté

fchapoton · 2020-05-17T09:11:53Z

comment:13

bot is morally green, please review

sagetrac-tmonteil · 2020-05-17T10:53:11Z

Reviewer: Thierry Monteil

vbraun · 2020-05-26T21:44:13Z

Changed branch from u/chapoton/28913 to 297033a

seblabbe · 2020-06-24T20:18:43Z

comment:16

Replying to @seblabbe:

Is the following
sage: integrate(sqrt(x + sqrt(x)), x, algorithm='giac')
an other instance of the problem described in this ticket?

Answer is no. I created #29966 for the other issue mentioned in comment 6.

seblabbe · 2020-06-24T20:18:43Z

Changed commit from 297033a to none

EmmanuelCharpentier mannequin added this to the sage-9.0 milestone Dec 26, 2019

EmmanuelCharpentier mannequin added c: calculus labels Dec 26, 2019

embray modified the milestones: sage-9.0, sage-9.1 Jan 6, 2020

mkoeppe modified the milestones: sage-9.1, sage-9.2 May 7, 2020

fchapoton added the s: needs review label May 16, 2020

sagetrac-tmonteil mannequin added s: positive review and removed s: needs review labels May 17, 2020

vbraun removed the s: positive review label May 26, 2020

vbraun closed this as completed in 58f004f May 26, 2020

seblabbe mentioned this issue Sep 1, 2021

integrate(sqrt(x + sqrt(x)), x, algorithm='giac') raises RuntimeError #29966

Closed

mwageringel mentioned this issue Aug 29, 2021

use libgiac instead of giac for integration #31873

Closed

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integrate(..., algorithm="giac"): Incorrect conversion to Sage #28913

integrate(..., algorithm="giac"): Incorrect conversion to Sage #28913

EmmanuelCharpentier mannequin commented Dec 26, 2019

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seblabbe commented Jun 24, 2020

seblabbe commented Jun 24, 2020

integrate(..., algorithm="giac"): Incorrect conversion to Sage #28913

integrate(..., algorithm="giac"): Incorrect conversion to Sage #28913

Comments

EmmanuelCharpentier mannequin commented Dec 26, 2019

EmmanuelCharpentier mannequin commented Dec 26, 2019

EmmanuelCharpentier mannequin commented Dec 26, 2019

mwageringel commented Dec 27, 2019

slel commented Dec 28, 2019

embray commented Jan 6, 2020

seblabbe commented Apr 21, 2020

fchapoton commented May 16, 2020

fchapoton commented May 16, 2020

fchapoton commented May 16, 2020

fchapoton commented May 16, 2020

fchapoton commented May 16, 2020

sagetrac-tmonteil mannequin commented May 16, 2020

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seblabbe commented Jun 24, 2020