Thanks. Where can I find out more about fast_float? Even after importing fast_float, "fast_float?" does not show any useful information.
Is it related to fast_arith? 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 -~----------~----~----~----~------~----~------~--~---
