I was aware of the fact that f = fast_float(f) might be dangerous so I tried ff = fast_float(f). Now I tried your modification, unfortunately the problem persists.
I got the problem after the action "restart worksheet" and run the script on the same cell by just changing the functions on which it calls on. I'm running SAGE 3.1.4 on a VMware player on a Windows Machine. I hope someone can reproduce what I have experienced and figure out what's going on. On Nov 14, 7:19 am, Marshall Hampton <[EMAIL PROTECTED]> wrote: > I'm not sure what exactly is happening, but it might be some side > effect of redefining f and g inside the function. The following > version works for me: > > def shaded_area_plot(f,g,c,d,a,b): > """ > Plots functions f and g from c to d and shades the region between > them from a to b. > """ > from sage.ext.fast_eval import fast_float > f1 = fast_float(f) > g1 = fast_float(g) > step = 0.01 > vf = [(x,f1(x)) for x in srange(a, (b+step), step)] > vg = [(x,g1(x)) for x in srange(b, (a-step), -step)] > sha = polygon(vf + vg, rgbcolor='grey') > return(plot(f1, (c,d)) + plot(g1, (c,d), rgbcolor='red') + sha) > > -M. hampton > > On Nov 14, 1:12 am, pong <[EMAIL PROTECTED]> wrote: > > > Also, let me apologize in advance if that's because some bugs in my > > script. But I hope someone can tell me why that's happening. > > > On Nov 13, 11:10 pm, pong <[EMAIL PROTECTED]> wrote: > > > > While working with fast_float, I find something extremely puzzling! > > > It's hard to explain but let me try: > > > > 0) I define shade_are_plot > > > 1) I run shade_area_plot( f1,g1, a1, b1, c1, d1) > > > 2) I restart the worksheet > > > 3) I run the definition cell again > > > 4) I run shade_area_plot(f2, g2, a2, b2, c2, d2) > > > > SAGE shows me the first plot (i.e. in the plot produced in (1)), if I > > > run step (4) again, SAGE will then show me the shaded area between f2 > > > and g2. In general, if I restart the worksheet again and run > > > shade_area_plot on another two graphs, SAGE will show me the first 2 > > > plots before show me the plot that I want. > > > > Why? > > > > On Nov 13, 1:59 pm, Robert Bradshaw <[EMAIL PROTECTED]> > > > wrote: > > > > > On Nov 13, 2008, at 1:22 PM, pong wrote: > > > > > > Thanks. > > > > > > Where can I find out more about fast_float? > > > > > Even after importing fast_float, "fast_float?" does not show any > > > > > useful information. > > > > > Try typing sage.ext.fast_eval? > > > > > > Is it related to fast_arith? > > > > > No, completely orthogonal despite the name. > > > > > > On Nov 12, 7:56 pm, Robert Bradshaw <[EMAIL PROTECTED]> > > > > > wrote: > > > > >> On Nov 12, 2008, at 5:52 PM, kcrisman wrote: > > > > > >>>> put those three lines in where indicated and it will be orders of > > > > >>>> magnitude faster for most cases, plus will handle constants, lambda > > > > >>>> functions, etc., automatically. > > > > > >>>> fast_float is one of Sage's coolest "secrets". > > > > > >> Thanks :) > > > > > >>> That brings up a question I've had for a while. When is it good to > > > > >>> use fast_float (I've seen a lot of code over the last few months > > > > >>> which > > > > >>> replaces other calls with it) and when is it not good, or for > > > > >>> instance > > > > >>> when might RR be better, or just nothing? E.g. William's > > > > >>> examples on > > > > >>> the interact wiki use it, but the others don't. Given the > > > > >>> limitations > > > > >>> of our Sage server, something like that could really help things > > > > >>> if it > > > > >>> really speeded it up. Unfortunately, as a non-CS type the > > > > >>> documentation just doesn't compute for me, and just seeing a > > > > >>> couple of > > > > >>> examples where it is good to use it and where it isn't would be very > > > > >>> helpful. > > > > > >>> For instance, should it only be used in .py files, or is it > > > > >>> worthwhile > > > > >>> in the command line or notebook? Is it worth using if something is > > > > >>> evaluated fewer than (say) 100 times? Can it be interspersed > > > > >>> with ZZ > > > > >>> (I assume not) or RR(n), say RR(1000) (I have no idea)? Thanks for > > > > >>> any examples, especially from non-high-performance situations > > > > >>> where it > > > > >>> still might speed things up considerably (or do something bad). > > > > > >> The fast_float functionality is mostly for internal use, and is > > > > >> useful when one wants to evaluate an expression to double floating- > > > > >> point (i.e. 53-bits using the machine's native arithmetic) lots of > > > > >> times. "Lots" depends on the application, but is probably in the > > > > >> neighborhood of 10-100+, depending on the complexity of the equation > > > > >> and whether or not it has any symbolic values like pi (which slow > > > > >> down "normal" evaluation via maxima a huge amount). Thus it is suited > > > > >> to things like plotting or numerical integration. However, most such > > > > >> functions internally construct fast_float objects, so there usually > > > > >> is no need for the user to do so. > > > > > >> That being said, there are plenty of use cases for it for end users. > > > > >> On the interact wiki (looking at the calculus page) it seems that > > > > >> fast_float is used when the function is evaluated a lot, and not when > > > > >> it is just passed off to something else (e.g. to contour_plot which > > > > >> (should) use the fast_float internally). The usage in "Coordinate > > > > >> Transformations" is probably redundant, as parametric_plot should be > > > > >> calling fast_float itself. > > > > > >> Not sure it completely answers your question, but hopefully it helps. > > > > > >> - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
