On Fri, Apr 2, 2010 at 3:30 PM, G B <[email protected]> wrote: > That did it. I found the section in the tutorial explaining the > different interpretations of functions more fully, and while I don't > quite have my head around it, I think I understand the problem at a > basic level to be that my f(x) is a symbolic expression, but > get_random_element() is a Python function, and there's some odd > interaction under the hood. > > Is this something that will ever be able to be worked around > (excepting things like trying to symbolically integrate a Python > function)? Is Sage doomed to have these similar but not quite > compatible entities interacting in strangely subtle ways, or is there
Yep. Except when you understand them, they do not seem similar or strange. William > the hope that as the package matures everything will begin to play > more nicely? > > My concern is that, as a newbie, I'm carefully double checking each > step of my calculation because I know that I don't know what I'm > doing-- but eventually I'm liable to gain confidence, lose track of > these various function types, and not realize that the results I'm > getting are incorrect. > > > On Mar 30, 7:04 pm, William Stein <[email protected]> wrote: >> On Tue, Mar 30, 2010 at 7:01 PM, G B <[email protected]> wrote: >> > Apologies for being dense, but I'm missing something. All three forms >> > ( f(x), def f(x) and f=lambda x: ) are giving the same results. >> >> > Trying: >> > --------- >> > var('x') >> > T=RealDistribution('gaussian',1) >> > def f(x): >> > return sin(x)+ T.get_random_element() >> > plot(f(x),(x,0,2*pi)) >> > --------- >> >> > and >> > -------- >> > var('x') >> > T=RealDistribution('gaussian',1) >> > f=lambda x: sin(x)+ T.get_random_element() >> > plot(f(x),(x,0,2*pi)) >> > --------- >> >> > all give me a clean sine with a random offset, rather than sine >> > +noise... >> >> Use >> >> plot(f, (0,2*pi)) >> >> William >> >> >> >> >> >> >> >> > On Mar 30, 2:30 pm, William Stein <[email protected]> wrote: >> >> On Tue, Mar 30, 2010 at 2:21 PM, G B <[email protected]> wrote: >> >> > Hi-- >> >> >> > I'm trying to figure out how to use RealDistributions to model noise. >> >> > For example, I would like to model a signal+noise and tried using this >> >> > construct: >> >> >> > T=RealDistribution('gaussian',1) >> >> > f(x)=sin(x)+T.get_random_element() >> >> > plot(f(x),(x,0,2*pi)) >> >> >> > Unfortunately, that only calls get_random_element() once, at the >> >> > definition of f(x) and results in a perfect sinusoid offset by a >> >> > random value. >> >> >> def f(x): >> >> return sin(x) + T.get_random_element() >> >> >> or >> >> >> f = lambda x : sin(x) + T.get_random_element() >> >> >> William >> >> >> > How do I write this so that get_random_element() is called each time >> >> > f(x) is evaluated? I would like to see a noisy sinusoid. >> >> >> > Thanks-- >> >> > Greg >> >> >> > -- >> >> > To post to this group, send email to [email protected] >> >> > To unsubscribe from this group, send email to >> >> > [email protected] >> >> > For more options, visit this group >> >> > athttp://groups.google.com/group/sage-support >> >> > URL:http://www.sagemath.org >> >> >> > To unsubscribe from this group, send email to >> >> > sage-support+unsubscribegooglegroups.com or reply to this email with >> >> > the words "REMOVE ME" as the subject. >> >> >> -- >> >> William Stein >> >> Associate Professor of Mathematics >> >> University of Washingtonhttp://wstein.org >> >> > -- >> > To post to this group, send email to [email protected] >> > To unsubscribe from this group, send email to >> > [email protected] >> > For more options, visit this group >> > athttp://groups.google.com/group/sage-support >> > URL:http://www.sagemath.org >> >> -- >> William Stein >> Associate Professor of Mathematics >> University of Washingtonhttp://wstein.org > > -- > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/sage-support > URL: http://www.sagemath.org > -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
