[Numpy-discussion] simulate AR

2011-10-14 Thread Alan G Isaac
As a simple example, if I have y0 and a white noise series e, what is the best way to produces a series y such that y[t] = 0.9*y[t-1] + e[t] for t=1,2,...? 1. How can I best simulate an autoregressive process using NumPy? 2. With SciPy, it looks like I could do this as e[0] = y0

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 10:24 AM, Alan G Isaac alan.is...@gmail.com wrote: As a simple example, if I have y0 and a white noise series e, what is the best way to produces a series y such that y[t] = 0.9*y[t-1] + e[t] for t=1,2,...? 1. How can I best simulate an autoregressive process using

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread Fabrice Silva
Le vendredi 14 octobre 2011 à 10:49 -0400, josef.p...@gmail.com a écrit : On Fri, Oct 14, 2011 at 10:24 AM, Alan G Isaac alan.is...@gmail.com wrote: As a simple example, if I have y0 and a white noise series e, what is the best way to produces a series y such that y[t] = 0.9*y[t-1] + e[t]

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 11:56 AM, Fabrice Silva si...@lma.cnrs-mrs.fr wrote: Le vendredi 14 octobre 2011 à 10:49 -0400, josef.p...@gmail.com a écrit : On Fri, Oct 14, 2011 at 10:24 AM, Alan G Isaac alan.is...@gmail.com wrote: As a simple example, if I have y0 and a white noise series e,

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 12:49 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 12:21 PM, josef.p...@gmail.com wrote: One other way to simulate the AR is to get the (truncated) MA-representation, and then convolve can be used Assuming stationarity ... maybe ? If it's integrated,

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread Alan G Isaac
Assuming stationarity ... On 10/14/2011 1:22 PM, josef.p...@gmail.com wrote: maybe ? I just meant that the MA approximation is not reliable for a non-stationary AR. E.g., http://www.jstor.org/stable/2348631 Cheers, Alan ___ NumPy-Discussion mailing

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 1:26 PM, Alan G Isaac alan.is...@gmail.com wrote: Assuming stationarity ... On 10/14/2011 1:22 PM, josef.p...@gmail.com wrote: maybe ? I just meant that the MA approximation is not reliable for a non-stationary AR. E.g., http://www.jstor.org/stable/2348631 section

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread Alan G Isaac
On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the starting values is a bit difficult. Hmm. Yes. AR(1) is trivial, but how do you handle higher orders? Thanks, Alan

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the starting values is a bit difficult. Hmm.  Yes. AR(1) is trivial, but how do

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread Skipper Seabold
On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the starting values is a bit difficult. Hmm.  Yes. AR(1) is trivial, but how

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 2:39 PM, Skipper Seabold jsseab...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 2:29 PM, josef.p...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the starting values

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 2:59 PM, josef.p...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:29 PM,  josef.p...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter