[sage-devel] Bug in solve?

[Florian Buerzle]

Sage version: 9.8beta3 (built on WSL Ubuntu)
Operating system: Windows 11

I tried to solve a logarithmic equation with solve, using algorithm='sympy':

var("x")
eq = log(x^2) == log(2*x,10)
solve(eq,x,algorithm='sympy')

The result was:

\displaystyle \verb|Complement(ConditionSet(x,|\verb| |\verb|Eq(x**2|\verb| 
|\verb|-|\verb| |\verb|(2*x)**(1/log(10)),|\verb| |\verb|0),|\verb| 
|\verb|Complexes),|\verb| |\verb|ConditionSet(x,|\verb| 
|\verb|Eq(x**(1/log(10)),|\verb| |\verb|0),|\verb| |\verb|Complexes))|


However, using sympy.solve directly

import sympy
var("x")
eq = log(x^2) == log(2*x,10)
sympy.solve(eq,x)

it returns the correct solution 

\displaystyle \left[\verb|2**(-1/(1|\verb| |\verb|-|\verb| 
|\verb|log(100)))|\right]

Is this a conversion bug into sympy input?

Best 
Florian







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[sage-devel] bug in solve?

[Johannes]

i just tried something with solving a equation, i think i did it the
wrong way, but still it should not result in this:

def calc_wights_by_sum(s)
variables = var([w + str(i) for i in range(s.nvertices())])
equation = reduce(lambda f1,f2: f1 + f2, [variables[i] * s.vertex(i)
for i in range(s.nvertices())]) == 0
print equation
return solve(equation,variables)

sage: calc_wights_by_sum(s)
False
Exception RuntimeError: 'maximum recursion depth exceeded in
__subclasscheck__' in type 'exceptions.RuntimeError' ignored
Exception RuntimeError: RuntimeError('maximum recursion depth exceeded
in cmp',) in Exception RuntimeError: 'maximum recursion depth exceeded
in __subclasscheck__' in type 'exceptions.RuntimeError' ignored
 ignored
Exception RuntimeError: 'maximum recursion depth exceeded in
__subclasscheck__' in type 'exceptions.RuntimeError' ignored
Exception RuntimeError: RuntimeError('maximum recursion depth exceeded
in cmp',) in Exception RuntimeError: 'maximum recursion depth exceeded
in __subclasscheck__' in type 'exceptions.RuntimeError' ignored
[...]

i just helped to kill python by killall -9 python.

greatz Johannes

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Re: [sage-devel] bug in solve?

[Johannes]

ok, i got my first mistake,
the first line in the functoin schould be this:
variables = [var(w + str(i))for i in range(s.nvertices())]

but anyway, no reason for such a big problem.


Am 29.07.2010 01:15, schrieb Johannes:
 i just tried something with solving a equation, i think i did it the
 wrong way, but still it should not result in this:

 def calc_wights_by_sum(s)
 variables = var([w + str(i) for i in range(s.nvertices())])
 equation = reduce(lambda f1,f2: f1 + f2, [variables[i] * s.vertex(i)
 for i in range(s.nvertices())]) == 0
 print equation
 return solve(equation,variables)

 sage: calc_wights_by_sum(s)
 False
 Exception RuntimeError: 'maximum recursion depth exceeded in
 __subclasscheck__' in type 'exceptions.RuntimeError' ignored
 Exception RuntimeError: RuntimeError('maximum recursion depth exceeded
 in cmp',) in Exception RuntimeError: 'maximum recursion depth exceeded
 in __subclasscheck__' in type 'exceptions.RuntimeError' ignored
  ignored
 Exception RuntimeError: 'maximum recursion depth exceeded in
 __subclasscheck__' in type 'exceptions.RuntimeError' ignored
 Exception RuntimeError: RuntimeError('maximum recursion depth exceeded
 in cmp',) in Exception RuntimeError: 'maximum recursion depth exceeded
 in __subclasscheck__' in type 'exceptions.RuntimeError' ignored
 [...]

 i just helped to kill python by killall -9 python.

 greatz Johannes

   

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