On Sunday 30 January 2011 16:35:15 Charles R Harris wrote:
> On Sat, Jan 29, 2011 at 10:11 PM, Algis Kabaila
wrote:
> > On Sunday 30 January 2011 09:10:30 Sturla Molden wrote:
> > > Den 29.01.2011 12:40, skrev Algis Kabaila:
> > > > So my question is: how can one reliably detect
> > > > singularit
On Sat, Jan 29, 2011 at 10:11 PM, Algis Kabaila wrote:
> On Sunday 30 January 2011 09:10:30 Sturla Molden wrote:
> > Den 29.01.2011 12:40, skrev Algis Kabaila:
> > > So my question is: how can one reliably detect singularity
> > > (or near singularity) and raise an exception?
> >
> > Use an SVD, e
On Sunday 30 January 2011 09:10:30 Sturla Molden wrote:
> Den 29.01.2011 12:40, skrev Algis Kabaila:
> > So my question is: how can one reliably detect singularity
> > (or near singularity) and raise an exception?
>
> Use an SVD, examine the singular values.
I gather that SVD is the Singular Valu
On Saturday 29 January 2011 22:47:23 Stuart Brorson wrote:
> > So my question is: how can one reliably detect singularity
> > (or near singularity) and raise an exception?
>
> Matrix condition number:
>
> http://docs.scipy.org/doc/numpy/reference/generated/numpy.lin
> alg.cond.html http://en.wiki
On Sat, Jan 29, 2011 at 5:30 PM, Charles R Harris
wrote:
>
>
> On Sat, Jan 29, 2011 at 2:01 PM, Nicolas SCHEFFER
> wrote:
>>
>> Hi all,
>>
>> First email to the list for me, I just want to say how grateful I am
>> to have python+numpy+ipython etc... for my day to day needs. Great
>> combination o
On Sat, Jan 29, 2011 at 6:58 PM, Jason Grout wrote:
> The SVD documentation seems a bit misleading. It says:
>
> Factors the matrix a as u * np.diag(s) * v, where u and v are unitary
> and s is a 1-d array of a‘s singular values.
>
> However, that only is true (i.e., you just have to do np.diag(s
On Sat, Jan 29, 2011 at 8:58 PM, Jason Grout
wrote:
> The SVD documentation seems a bit misleading. It says:
>
> Factors the matrix a as u * np.diag(s) * v, where u and v are unitary
> and s is a 1-d array of a‘s singular values.
>
> However, that only is true (i.e., you just have to do np.diag(s
The SVD documentation seems a bit misleading. It says:
Factors the matrix a as u * np.diag(s) * v, where u and v are unitary
and s is a 1-d array of a‘s singular values.
However, that only is true (i.e., you just have to do np.diag(s) to get
S) in general if full_matrices is False, which is no
Hi,
On Sat, Jan 29, 2011 at 11:01 PM, Nicolas SCHEFFER <
scheffer.nico...@gmail.com> wrote:
> Hi all,
>
> First email to the list for me, I just want to say how grateful I am
> to have python+numpy+ipython etc... for my day to day needs. Great
> combination of software.
>
> Anyway, I've been havi
Didn't I recommend the C++ and Fortran versions of 2nd edition? I
particularly like the Fortran 90 edition as NumPy behaves like a vector
machine as well. (The algorithms are explained in the Fortran 77 text,
so they must be read together.)
I'd like to warn against NR in C (all algorithms cont
On Sat, Jan 29, 2011 at 2:01 PM, Nicolas SCHEFFER <
scheffer.nico...@gmail.com> wrote:
> Hi all,
>
> First email to the list for me, I just want to say how grateful I am
> to have python+numpy+ipython etc... for my day to day needs. Great
> combination of software.
>
> Anyway, I've been having thi
Den 29.01.2011 12:40, skrev Algis Kabaila:
> So my question is: how can one reliably detect singularity (or
> near singularity) and raise an exception?
Use an SVD, examine the singular values. One or more small singular
values indicate ill-conditioning. (What constitutes a small singular
value i
Thanks for the prompt reply!
I quickly tried that and it actually helps compared to the full
vectorized version.
Depending on the dimensions, the chunk size has to be tuned (typically
100 or so)
But I don't get any improvement w/r to the simple for loop (i can
almost match the time though).
My gue
On Saturday, January 29, 2011, Nicolas SCHEFFER
wrote:
> Hi all,
>
> First email to the list for me, I just want to say how grateful I am
> to have python+numpy+ipython etc... for my day to day needs. Great
> combination of software.
>
> Anyway, I've been having this bottleneck in one my algorithm
Hi all,
First email to the list for me, I just want to say how grateful I am
to have python+numpy+ipython etc... for my day to day needs. Great
combination of software.
Anyway, I've been having this bottleneck in one my algorithms that has
been bugging me for quite a while.
The objective is to sp
> So my question is: how can one reliably detect singularity (or
> near singularity) and raise an exception?
Matrix condition number:
http://docs.scipy.org/doc/numpy/reference/generated/numpy.linalg.cond.html
http://en.wikipedia.org/wiki/Condition_number
Stuart
__
Hi,
I am interested in determining if a matrix is singular or
"nearly singular" - very ill conditioned. The problem occurs in
structural engineering applications.
My OS is kubuntu 10.10 (32 bit)
Python 2.6.6
numpy and numpy.linalg binaries from ubuntu repositories.
The attached tar ball has
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