On Tue, Oct 27, 2009 at 10:55 AM, all_thumbs <sch...@hsva.de> wrote: > Hi Dave, > > On Jul 22, 12:56 am, David Joyner <wdjoy...@gmail.com> wrote: > ... >> I'm not sure what you are going to do with yourfunction. >> If it is just for plotting, say, I think you might just want to use >> >> def f(x,y): >> if <case1>: >> return <whatever1> >> if <case2>: >> return <whatever2> >> etc
> > I have recently installed SAGE in the hope that I can cut down a bit > on > all the odd math tools that I use today. One of the very first things > I tried, > inspired by the calculus quick reference page, was the piecewise > function. > > I quickly found out that a (very simple) function f defined with > piecewise > cannot be plotted with "plot(f, ....)", but works fine with "f.plot > ()". On the > other hand, the same function defined as a python function as above, > does not plot properly. Oddly enough, when I define abs(x) like this: > > def f(x): > if x < 0 : > return -x > else : > return x > > only the last branch of the conditional statement is visible in the > diagram. > On the other hand, this branch is visible for all input values, x<0 > too! You could try: sage: f = lambda x: x > 0 and 1 or -1 sage: plot(f,x,-2,2) > > So, even if only need to plot a function, SAGE seems to have some > troubles with functions that are defined in pieces. > Yes, the Piecewise class was written some time ago and badly needs revision. Hopefully someone will volunteer to work on it more. > Johannes --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
