Status: New
Owner: ----
Labels: Type-Defect Priority-Critical
New issue 3653 by alessand...@gmail.com: solve does not return zero roots
when solving a system of equation
http://code.google.com/p/sympy/issues/detail?id=3653
with Python 3.2.3. and sympy 0.7.2. I obtain:
Python 3.2.3 (default, Oct 19 2012, 19:53:57)
[GCC 4.7.2] on linux2
Type "copyright", "credits" or "license()" for more information.
import sympy
sympy.__version__
'0.7.2'
a,b,c = sympy.var('a b c')
sympy.solve([a**2 + a, a -b], [a,b])
{b: -1, a: -1}
sympy.solve([a**2 + a*c, a - b], [a,b])
{b: -c, a: -c}
THIS WAS THE WRONG RESULT. (The root (a,b)=(0,0) is missing !)
But in Python 2.7.3 and Sympy 0.7.1.rc1 I obtain the correct result. Here
the code
Python 2.7.3 (default, Sep 26 2012, 21:53:58)
[GCC 4.7.2] on linux2
Type "copyright", "credits" or "license()" for more information.
import sympy
sympy.__version__
'0.7.1.rc1'
a,b,c = sympy.var('a b c')
sympy.solve([a**2 + a, a-b], [a,b])
[(-1, -1), (0, 0)]
sympy.solve([a**2 + a*c, a-b], [a,b])
[(0, 0), (-c, -c)]
and there seems to be other issues with solve: in finding roots of
equations of grade 5 in some versions the roots are not found, and in
others the result can be RootOf with resulting wrong multiplicity of the
roots. There was already a post on this.
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