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