[sage-support] Additionnal constraints are never enough

[Maxim]

Hello, I'd like to know if it's possible to get Sage to process the
following integrals:

reset()
var('x y z')
assume(z-16)
assume(z0)
integrate(integrate(1/16,y,-2,(z+2*x+4)/(x+2)),x,(-z-8)/4,2)

Sage always return: Is  z+16  positive, negative, or zero?

Maxim

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Re: [sage-support] Additionnal constraints are never enough

[D. S. McNeil]

 integrate(integrate(1/16,y,-2,(z+2*x+4)/(x+2)),x,(-z-8)/4,2)

Seems to work for me:

--
| Sage Version 4.6.1, Release Date: 2011-01-11   |
| Type notebook() for the GUI, and license() for information.|
--
sage: var(x y z)
(x, y, z)
sage: integrate(integrate(1/16,y,-2,(z+2*x+4)/(x+2)),x,(-z-8)/4,2)
[...]
TypeError: Computation failed since Maxima requested additional
constraints (try the command 'assume(z+160)' before integral or limit
evaluation, for example):
Is  z+16  positive, negative, or zero?
sage: assume(z+160)
sage: integrate(integrate(1/16,y,-2,(z+2*x+4)/(x+2)),x,(-z-8)/4,2)
[...]
TypeError: Computation failed since Maxima requested additional
constraints (try the command 'assume(z0)' before integral or limit
evaluation, for example):
Is  z  positive, negative, or zero?
sage: assume(z0)
sage: integrate(integrate(1/16,y,-2,(z+2*x+4)/(x+2)),x,(-z-8)/4,2)
-1/16*z*log(-1/4*z) + 1/16*z*log(4) + 1/16*z + 1

What version of Sage are you running?  (Note that 4.6.2 has just been released.)


Doug

--
Department of Earth Sciences
University of Hong Kong

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