On Feb 8, 2:17 pm, dk <dan.kel...@dal.ca> wrote:
Hi,
> First, an apology: I am not sure I'm doing this entirely correctly.
Nah, this sounds about right, in case it is above average. For some
reason it seems that the moderation system the groups have is racy
since this email showed up twice :)
> Commands typed
> ==============
>
> from scipy.signal.filter_design import *
> butter(2,0.5)
>
> Result
> =====
>
> An error (traceback given below).
>
> Expected result
> ============
>
> The expected output was a list of coefficients for the moving-average
> and recursive parts of a Butterworth digital filter.
>
> System
> ======
> Mac OSX running Sage Version 3.2.3, Release Date:
> 2009-01-05 |
>
> Traceback
> ========
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/Users/kelley/.sage/sage_notebook/worksheets/admin/7/code/
> 10.py",
> line 7, in <module>
> butter(_sage_const_2 ,_sage_const_0p5 )
> File "/Applications/sage/local/lib/python2.5/site-packages/
> SQLAlchemy-0.4.6-py2.5.egg/",
> line 1, in <module>
>
> File "/Applications/sage/local/lib/python2.5/site-packages/scipy/
> signal/filter_design.py",
> line 482, in butter
> return iirfilter(N, Wn, btype=btype, analog=analog, output=output,
> ftype='butter')
> File "/Applications/sage/local/lib/python2.5/site-packages/scipy/
> signal/filter_design.py",
> line 434, in iirfilter
> z, p, k = typefunc(N)
> File "/Applications/sage/local/lib/python2.5/site-packages/scipy/
> signal/filter_design.py",
> line 957, in buttap
> p = numpy.exp(1j*(2*n-1)/(2.0*N)*pi)*1j
> AttributeError: exp
We are running the last official release (indeed, we run some svn
release after that), but it is way out of date compared to scipy
0.7.rc2. The plan is to update to that in the near future, but so far
every time we tried something else got in the way.
It might be nice to try this in pure python and with scipy 0.7.rc2 and
in case this is supposed to work and still broken complain to the
scipy folks and open a ticket in their tracker. Until then we should
open a ticket in Sage's trac so we add a doctest that verifies this
works (assuming it is a bug :) once we update to scipy 0.7.
Cheers,
Michael
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