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 -~----------~----~----~----~------~----~------~--~---
