#13049: solve(A*x+C*y^B, y) returns maxima error without explanation
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Reporter: gutow | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-5.1
Component: symbolics | Keywords: solve, maxima, exponents
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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Possibly related ticket #8659
Example of problem
{{{
sage: var ('x y z A B C')
sage: f = A*x + C*y^B
sage: solve(f==0, y)
}}}
returns
{{{
Traceback (click to the left of this block for traceback)
...
TypeError: ECL says: Maxima asks: Is B an integer?
}}}
At the very least this should return a message more like those in
sage/symbolic/integration/integration.py. Something along the lines of:
"Solve failed because Maxima requested contraints; using the 'assume'
command before 'solve' may help (e.g. 'assume( B, 'integer')'). See
'assume?' for more info." The Maxima error should also be passed on.
However, I would prefer to see the general symbolic solution unless
numeric values are assigned to the variables in the expression. Note that
'assume(B, 'integer') gives what I consider the correct general symbolic
expression:
{{{
sage: var ('x y z A B C')
sage: f = A*x + C*y^B
sage: assume(B, 'integer')
sage: solve(f==0, y)
[y == (-A*x/C)^(1/B)]
}}}
For a little discussion of this see sage-devel:
https://groups.google.com/forum/#!topic/sage-devel/AQUV9hHUqXI
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13049>
Sage <http://www.sagemath.org>
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