So, I was surprised by the results of interrupting the code after
different execution times. I assumed it was hanging in the matrix
inverse. It actually completes the inverse in a minute or so and then
spends the rest of the time trying to use the results of the inverse
to compute several vectors. The full traceback is below, but it hangs
on this line:
/home/ryan/git/sympy/sympy/core/power.pyc in _eval_expand_basic(self)
258 (a+b+..) ** n -> a**n + n*a**(n-1)*b + .., n is positive integer
259 """
--> 260 b = self.base._eval_expand_basic()
261 e = self.exp._eval_expand_basic()
262
The toplevel calculation that is causing the problem is here:
/home/ryan/git/research/sympy_TMM.pyc in find_base_vector(Uin)
310 submati = find_submat_inv(Uin)
311 Uc4 = Uin[2:4,4]
--> 312 MbVb = -1.0*(submati*Uc4)
313 z_b = zeros((5,1))
314 z_b[2] = MbVb[0]
submati is a 2x2 matrix of fairly complicated terms. Uc4 is a 2x1
column vector.
Ryan
Full traceback:
In [5]: run symbolic_poles_and_zeros.py
^C---------------------------------------------------------------------------
KeyboardInterrupt Traceback (most recent call last)
/home/ryan/siue/Research/papers/SFLR_2010_paper/python/symbolic_poles_and_zeros.py
in <module>()
6
7 mymodel = JVC_model.model_w_bm()
----> 8 mymodel.find_symbolic_bodes(save=0)
9
10
/home/ryan/siue/Research/papers/SFLR_2010_paper/python/JVC_model.pyc
in find_symbolic_bodes(self, save)
740 U6 = beam2.Get_Aug_Mat(s)
741 Usys = U6*(U5*(U4*(U3*(U2*(U1*U0)))))
--> 742 z_b = sympy_TMM.find_base_vector(Usys)
743 z_enc = U2*(U1*(U0*z_b))
744 enc_gain = 180.0/pi*1024.0/360.0
/home/ryan/git/research/sympy_TMM.pyc in find_base_vector(Uin)
310 submati = find_submat_inv(Uin)
311 Uc4 = Uin[2:4,4]
--> 312 MbVb = -1.0*(submati*Uc4)
313 z_b = zeros((5,1))
314 z_b[2] = MbVb[0]
/home/ryan/git/sympy/sympy/matrices/matrices.pyc in __mul__(self, a)
399 def __mul__(self,a):
400 if hasattr(a, "__array__"):
--> 401 return matrix_multiply(self,a)
402 out = Matrix(self.lines,self.cols,map(lambda i: i*a,self.mat))
403 return out
/home/ryan/git/sympy/sympy/matrices/matrices.pyc in matrix_multiply(A, B)
1483 blst = B.T.tolist()
1484 alst = A.tolist()
-> 1485 return Matrix(A.shape[0], B.shape[1], lambda i,j:
1486 reduce(lambda k,l: k+l,
1487 map(lambda n,m: n*m,
/home/ryan/git/sympy/sympy/matrices/matrices.pyc in __init__(self, *args)
87 for i in range(self.lines):
88 for j in range(self.cols):
---> 89 self.mat.append(sympify(operation(i, j)))
90 elif len(args)==3 and isinstance(args[0],int) and \
91 isinstance(args[1],int) and
isinstance(args[2], (list, tuple)):
/home/ryan/git/sympy/sympy/matrices/matrices.pyc in <lambda>(i, j)
1487 map(lambda n,m: n*m,
1488 alst[i],
-> 1489 blst[j])).expand())
1490 # .expand() is a test
1491
/home/ryan/git/sympy/sympy/core/basic.pyc in expand(self, **hints)
1477 if not 'basic' in hints:
1478 if not expr.is_Atom:
-> 1479 result = expr._eval_expand_basic()
1480
1481 if result is not None:
/home/ryan/git/sympy/sympy/core/basic.pyc in _eval_expand_basic(self)
1403 terms.append(term)
1404 else:
-> 1405 T = term._eval_expand_basic()
1406
1407 if T is None:
/home/ryan/git/sympy/sympy/core/mul.pyc in _eval_expand_basic(self)
396 else:
397 if sums:
--> 398 terms = Mul._expandsums(sums)
399
400 if isinstance(terms, Basic):
/home/ryan/git/sympy/sympy/core/mul.pyc in _expandsums(sums)
363 for a in left:
364 for b in right:
--> 365 terms.append(Mul(a,b).expand())
366 added = Add(*terms)
367 if added.is_Add:
/home/ryan/git/sympy/sympy/core/basic.pyc in expand(self, **hints)
1477 if not 'basic' in hints:
1478 if not expr.is_Atom:
-> 1479 result = expr._eval_expand_basic()
1480
1481 if result is not None:
/home/ryan/git/sympy/sympy/core/mul.pyc in _eval_expand_basic(self)
375
376 for factor in self.args:
--> 377 terms = factor._eval_expand_basic()
378
379 if terms is not None:
/home/ryan/git/sympy/sympy/core/power.pyc in _eval_expand_basic(self)
258 (a+b+..) ** n -> a**n + n*a**(n-1)*b + .., n is positive integer
259 """
--> 260 b = self.base._eval_expand_basic()
261 e = self.exp._eval_expand_basic()
262
/home/ryan/git/sympy/sympy/core/basic.pyc in _eval_expand_basic(self)
1403 terms.append(term)
1404 else:
-> 1405 T = term._eval_expand_basic()
1406
1407 if T is None:
/home/ryan/git/sympy/sympy/core/mul.pyc in _eval_expand_basic(self)
375
376 for factor in self.args:
--> 377 terms = factor._eval_expand_basic()
378
379 if terms is not None:
/home/ryan/git/sympy/sympy/core/power.pyc in _eval_expand_basic(self)
258 (a+b+..) ** n -> a**n + n*a**(n-1)*b + .., n is positive integer
259 """
--> 260 b = self.base._eval_expand_basic()
261 e = self.exp._eval_expand_basic()
262
/home/ryan/git/sympy/sympy/core/basic.pyc in _eval_expand_basic(self)
1403 terms.append(term)
1404 else:
-> 1405 T = term._eval_expand_basic()
1406
1407 if T is None:
/home/ryan/git/sympy/sympy/core/mul.pyc in _eval_expand_basic(self)
390
391 if terms is not None:
--> 392 rewrite = True
393
394 if not rewrite:
KeyboardInterrupt:
WARNING: Failure executing file: <symbolic_poles_and_zeros.py>
On Thu, Oct 21, 2010 at 7:16 AM, Øyvind Jensen <[email protected]> wrote:
> to., 21.10.2010 kl. 06.43 -0500, skrev Ryan Krauss:
>> Thanks for the suggestion. I will see if I can find a place to clear
>> the cache. Ironically, the slower machine has more RAM than the fast
>> one.
>
> Oh, well then maybe the problem is something else. clear_cache is only
> useful if you are running out of RAM.
>
>>
>> I didn't know what generic-pae meant until I just googled it. I guess
>> it is a way to allow 32-bit machines to have more than 3 GB of RAM.
>> The laptop has 4 GB. Does the fact that the kernel is using a generic
>> processor cause problems?
>>
>
> Sorry, I don't know much about hardware.
>
> Sometimes Sympy can behave slightly different on two computers because
> certain functionalities in Python are platform dependent, like the hash.
> However, differences should only occur for unimportant things, such as
> the order of terms in an expression.
>
> If there is a specific statement where a hang occurs, it may indicate an
> issue that is triggered only on certain platforms. Could you see if you
> get the same traceback every time you kill the hanging script? (or
> almost the same) In that case, could you post it here?
>
> Øyvind
>
>> Thanks,
>>
>> Ryan
>>
>> On Thu, Oct 21, 2010 at 6:37 AM, Øyvind Jensen <[email protected]>
>> wrote:
>> >> Any idea what could make this machine so unhappy to run sympy?
>> >
>> > In my (limited) experience, memory is the bottle-neck when you see the
>> > kind of slow down you describe. You may try to clear the cache at some
>> > point in your calculation.
>> >
>> >>>> from sympy.core.cache import clear_cache
>> >>>> clear_cache()
>> >
>> > Øyvind
>> >
>> >>
>> >> Thanks,
>> >>
>> >> Ryan
>> >>
>> >
>> > --
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>> > To unsubscribe from this group, send email to
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>> >
>> >
>>
>
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