Status: Started
Owner: asmeurer
CC: mattpap
Labels: Type-Defect Priority-Medium NeedsReview Polynomial
New issue 1883 by asmeurer: Recode dmp_zero_p to be non-recursive
http://code.google.com/p/sympy/issues/detail?id=1883
A simple cProfile.run('integrate(x**2*exp(x)*sin(x), x)', sort=1)
reveals that most of the time is spent in dmp_zero_p for this integral.
However, it was coded recursively, when it is trivial to code it
non-recursively. This makes it faster:
In [11]: def rec_dmp_zero_p(f, u): # this is the old version
if not u:
return not f
else:
if len(f) == 1:
return rec_dmp_zero_p(f[0], u - 1)
else:
....: return False
....:
....:
In [18]: def non_rec_dmp_zero_p(f, u): # this is the new version
....: while u:
....: if len(f) != 1:
....: return False
....: f = f[0]
....: u -= 1
....: return not f
....:
In [19]: f =
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[-3]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]]]
In [24]: u = 46
In [25]: rec_dmp_zero_p(f, u)
Out[25]: False
In [26]: non_rec_dmp_zero_p(f, u)
Out[26]: False
In [27]: g =
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[]]]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]
In [28]: rec_dmp_zero_p(g, u)
Out[28]: True
In [29]: non_rec_dmp_zero_p(g, u)
Out[29]: True
In [30]: %timeit rec_dmp_zero_p(f, u)
10000 loops, best of 3: 23.8 us per loop
In [31]: %timeit non_rec_dmp_zero_p(f, u)
100000 loops, best of 3: 14.3 us per loop
In [32]: %timeit rec_dmp_zero_p(g, u)
10000 loops, best of 3: 22.8 us per loop
In [33]: %timeit non_rec_dmp_zero_p(g, u)
100000 loops, best of 3: 15.1 us per loop
And in the end, we find that the integral runs a little faster:
Before:
In [1]: %timeit integrate(x**2*exp(x)*sin(x), x)
1 loops, best of 3: 7.49 s per loop
After:
In [1]: %timeit integrate(x**2*exp(x)*sin(x), x)
1 loops, best of 3: 6.27 s per loop
Fix is at http://github.com/asmeurer/sympy/tree/non-rec-dmp_zero_p. Please
review.
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