Re: [Numpy-discussion] On the quality of the numpy.random.normal() distribution

2008-12-11 Thread Michael Gilbert
Bruce Carneal did some tests of robustness and speed for various normal generators. I don't know what his final tests showed for Box-Muller. IIRC, it had some failures but nothing spectacular. The tests were pretty stringent and based on using the erf to turn the normal distribution into a

[Numpy-discussion] On the quality of the numpy.random.normal() distribution

2008-12-10 Thread Michael Gilbert
Hello, I have been reading that there may be potential issues with the Box-Muller transform, which is used by the numpy.random.normal() function. Supposedly, since f*x1 and f*x2 are not independent variables, then the individual elements (corresponding to f*x1 and f*x2 ) of the distribution

Re: [Numpy-discussion] On the quality of the numpy.random.normal() distribution

2008-12-10 Thread Matthieu Brucher
I think the use of a correct uniform generator will allow a good normal distribution. Congruental generators are very basic generators, everyone knows they should not be used. I think Numpy uses a Mersenne Twisted generator, for which you can generate independant vectors with several hundred

Re: [Numpy-discussion] On the quality of the numpy.random.normal() distribution

2008-12-10 Thread Pauli Virtanen
Wed, 10 Dec 2008 14:03:39 -0500, Michael Gilbert wrote: I have been reading that there may be potential issues with the Box-Muller transform, which is used by the numpy.random.normal() function. Supposedly, since f*x1 and f*x2 are not independent variables, then the individual elements

Re: [Numpy-discussion] On the quality of the numpy.random.normal() distribution

2008-12-10 Thread Charles R Harris
On Wed, Dec 10, 2008 at 12:03 PM, Michael Gilbert [EMAIL PROTECTED] wrote: Hello, I have been reading that there may be potential issues with the Box-Muller transform, which is used by the numpy.random.normal() function. Supposedly, since f*x1 and f*x2 are not independent variables,