Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Pauli Virtanen
Hi, 16.02.2012 06:09, josef.p...@gmail.com kirjoitti: [clip] numpy linalg.svd doesn't produce always the same results running this gives two different answers, using scipy.linalg.svd I always get the same answer, which is one of the numpy answers (numpy random.multivariate_normal is

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread josef . pktd
On Thu, Feb 16, 2012 at 4:44 AM, Pauli Virtanen p...@iki.fi wrote: Hi, 16.02.2012 06:09, josef.p...@gmail.com kirjoitti: [clip] numpy linalg.svd doesn't produce always the same results running this gives two different answers, using scipy.linalg.svd I always get the same answer, which is

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Pauli Virtanen
16.02.2012 14:14, josef.p...@gmail.com kirjoitti: [clip] We had other cases of several patterns in quasi-deterministic linalg before, but as far as I remember only in the final digits of precision, where it didn't matter much except for reducing test precision in my cases. In the random

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread josef . pktd
On Thu, Feb 16, 2012 at 8:45 AM, Pauli Virtanen p...@iki.fi wrote: 16.02.2012 14:14, josef.p...@gmail.com kirjoitti: [clip] We had other cases of several patterns in quasi-deterministic linalg before, but as far as I remember only in the final digits of precision, where it didn't matter much

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Pauli Virtanen
16.02.2012 14:54, josef.p...@gmail.com kirjoitti: [clip] If I interpret you correctly, this should be a svd ticket, or an svd ticket as duplicate ? I think it should be a multivariate normal ticket. Fixing SVD is in my opinion not sensible: its only guarantee is that A = U S V^H down to

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread josef . pktd
On Thu, Feb 16, 2012 at 9:08 AM, Pauli Virtanen p...@iki.fi wrote: 16.02.2012 14:54, josef.p...@gmail.com kirjoitti: [clip] If I interpret you correctly, this should be a svd ticket, or an svd ticket as duplicate ? I think it should be a multivariate normal ticket. Fixing SVD is in my

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Warren Weckesser
On Thu, Feb 16, 2012 at 10:12 AM, Pierre Haessig pierre.haes...@crans.orgwrote: Le 16/02/2012 16:20, josef.p...@gmail.com a écrit : I don't see any way to fix multivariate_normal for this case, except for dropping svd or for random perturbing a covariance matrix with multiplicity of

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Robert Kern
On Thu, Feb 16, 2012 at 16:12, Pierre Haessig pierre.haes...@crans.org wrote: Le 16/02/2012 16:20, josef.p...@gmail.com a écrit : I don't see any way to fix multivariate_normal for this case, except for dropping svd or for random perturbing a covariance matrix with multiplicity of singular

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread josef . pktd
On Thu, Feb 16, 2012 at 11:20 AM, Warren Weckesser warren.weckes...@enthought.com wrote: On Thu, Feb 16, 2012 at 10:12 AM, Pierre Haessig pierre.haes...@crans.org wrote: Le 16/02/2012 16:20, josef.p...@gmail.com a écrit : I don't see any way to fix multivariate_normal for this case, except

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread josef . pktd
On Thu, Feb 16, 2012 at 11:30 AM, josef.p...@gmail.com wrote: On Thu, Feb 16, 2012 at 11:20 AM, Warren Weckesser warren.weckes...@enthought.com wrote: On Thu, Feb 16, 2012 at 10:12 AM, Pierre Haessig pierre.haes...@crans.org wrote: Le 16/02/2012 16:20, josef.p...@gmail.com a écrit : I

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Nathaniel Smith
On Thu, Feb 16, 2012 at 2:08 PM, Pauli Virtanen p...@iki.fi wrote: 16.02.2012 14:54, josef.p...@gmail.com kirjoitti: [clip] If I interpret you correctly, this should be a svd ticket, or an svd ticket as duplicate ? I think it should be a multivariate normal ticket. Fixing SVD is in my

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread josef . pktd
On Thu, Feb 16, 2012 at 11:47 AM, josef.p...@gmail.com wrote: On Thu, Feb 16, 2012 at 11:30 AM,  josef.p...@gmail.com wrote: On Thu, Feb 16, 2012 at 11:20 AM, Warren Weckesser warren.weckes...@enthought.com wrote: On Thu, Feb 16, 2012 at 10:12 AM, Pierre Haessig pierre.haes...@crans.org

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Robert Kern
On Thu, Feb 16, 2012 at 17:07, josef.p...@gmail.com wrote: cholesky is also deterministic in my runs We will need to check a variety of builds with different LAPACK libraries and also different matrix sizes to be sure. Alas! -- Robert Kern I have come to believe that the whole world is an

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Charles R Harris
On Thu, Feb 16, 2012 at 10:07 AM, josef.p...@gmail.com wrote: On Thu, Feb 16, 2012 at 11:47 AM, josef.p...@gmail.com wrote: On Thu, Feb 16, 2012 at 11:30 AM, josef.p...@gmail.com wrote: On Thu, Feb 16, 2012 at 11:20 AM, Warren Weckesser warren.weckes...@enthought.com wrote: On Thu,

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Pauli Virtanen
Hi, 16.02.2012 18:00, Nathaniel Smith kirjoitti: [clip] I agree, but the behavior is still surprising -- people reasonably expect something like svd to be deterministic. So there's probably a doc bug for alerting people that their reasonable expectation is, in fact, wrong :-). The problem

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Charles R Harris
On Thu, Feb 16, 2012 at 10:20 AM, Pauli Virtanen p...@iki.fi wrote: Hi, 16.02.2012 18:00, Nathaniel Smith kirjoitti: [clip] I agree, but the behavior is still surprising -- people reasonably expect something like svd to be deterministic. So there's probably a doc bug for alerting people

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Gael Varoquaux
On Thu, Feb 16, 2012 at 05:00:29PM +, Nathaniel Smith wrote: I agree, but the behavior is still surprising -- people reasonably expect something like svd to be deterministic. People are wrong then. Trust me, I work enough with ill-conditionned problems, including SVDs, to know that the

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-16 Thread Nathaniel Smith
On Thu, Feb 16, 2012 at 5:20 PM, Pauli Virtanen p...@iki.fi wrote: Hi, 16.02.2012 18:00, Nathaniel Smith kirjoitti: [clip] I agree, but the behavior is still surprising -- people reasonably expect something like svd to be deterministic. So there's probably a doc bug for alerting people that

[Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-15 Thread josef . pktd
Doing a bit of browsing in the numpy tracker, I found this. From my search this was not discussed on the mailing list. http://projects.scipy.org/numpy/ticket/1842 The multivariate normal random sample is not always the same, even though a seed is specified. It seems to alternate randomly

Re: [Numpy-discussion] strange behavior of numpy.random.multivariate_normal, ticket:1842

2012-02-15 Thread josef . pktd
On Wed, Feb 15, 2012 at 10:52 PM, josef.p...@gmail.com wrote: Doing a bit of browsing in the numpy tracker, I found this. From my search this was not discussed on the mailing list. http://projects.scipy.org/numpy/ticket/1842 The multivariate normal random sample is not always the same, even