Comment #2 on issue 1844 by smi...@gmail.com: expand methods pruned
http://code.google.com/p/sympy/issues/detail?id=1844
My attempts at getting expand fix have never caught on (#1725, #1849, and
this issue), so I will just record here a suggestion that is easiest to
implement: use cacheit. Then any repeated request will quickly resolve
instead of repeating the substitution process. The only problem is that
keywords to functions are converted to bools and this causes problems:
File "c:\users\leslie\sympy\sympy\core\tests\test_functions.py", line
222, in
test_expand_function
assert expand((x + y)**11, modulus=11) == x**11 + y**11
File "C:\Users\leslie\sympy\sympy\core\function.py", line 1562, in expand
return sympify(e).expand(deep=deep, modulus=modulus, **hints)
File "C:\Users\leslie\sympy\sympy\core\cache.py", line 101, in wrapper
func_cache_it_cache[k] = r = func(*args, **kw_args)
File "C:\Users\leslie\sympy\sympy\core\expr.py", line 1929, in expand
if not modulus.is_Integer or modulus <= 0:
AttributeError: 'bool' object has no attribute 'is_Integer'
If keywords having argument of only 0 or 1 are bool'ified then expand can
be decorated and the time to compute the solution to
var('u',real=True)
eq=u - (x**2 + y**2 + 1)*x/(x**2 + y**2)
drops from 76 seconds to 3 seconds: most of that time is spent in expand.
The expression is not very complicated, so even 3 seconds seems like a long
time:
[u/3 + (-u**2/9 + y**2/3 + 1/3)/((-1/2 + sqrt(3)*I/2)*(-u**3/27 - u*y**2/2
+ u*(
y**2 + 1)/6 + sqrt((-u**2/9 + y**2/3 + 1/3)**3 + (-2*u**3/27 - u*y**2 +
u*(y**2
+ 1)/3)**2/4))**(1/3)) - (-1/2 + sqrt(3)*I/2)*(-u**3/27 - u*y**2/2 +
u*(y**2 + 1
)/6 + sqrt((-u**2/9 + y**2/3 + 1/3)**3 + (-2*u**3/27 - u*y**2 + u*(y**2 +
1)/3)*
*2/4))**(1/3), u/3 + (-u**2/9 + y**2/3 + 1/3)/((-1/2 -
sqrt(3)*I/2)*(-u**3/27 -
u*y**2/2 + u*(y**2 + 1)/6 + sqrt((-u**2/9 + y**2/3 + 1/3)**3 + (-2*u**3/27
- u*y
**2 + u*(y**2 + 1)/3)**2/4))**(1/3)) - (-1/2 - sqrt(3)*I/2)*(-u**3/27 -
u*y**2/2
+ u*(y**2 + 1)/6 + sqrt((-u**2/9 + y**2/3 + 1/3)**3 + (-2*u**3/27 - u*y**2
+ u*
(y**2 + 1)/3)**2/4))**(1/3), u/3 + (-u**2/9 + y**2/3 + 1/3)/(-u**3/27 -
u*y**2/2
+ u*(y**2 + 1)/6 + sqrt((-u**2/9 + y**2/3 + 1/3)**3 + (-2*u**3/27 - u*y**2
+ u*
(y**2 + 1)/3)**2/4))**(1/3) - (-u**3/27 - u*y**2/2 + u*(y**2 + 1)/6 +
sqrt((-u**
2/9 + y**2/3 + 1/3)**3 + (-2*u**3/27 - u*y**2 + u*(y**2 +
1)/3)**2/4))**(1/3)]
https://github.com/sympy/sympy/pull/583
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