On Dec 3, 2008, at 10:42 AM, Jason Grout wrote: > Robert Bradshaw wrote: >> On Dec 3, 2008, at 5:55 AM, Stan Schymanski wrote: >> >>> Dear all, >>> >>> Could anyone tell me how to controll the order in which arguments >>> are >>> evaluated when they are passed to python functions? It seems that >>> the >>> functions are evaluated first and then the variables are >>> substituted, >>> which leads to failures in the following example: >> >> To answer the original question, Python doesn't give control over >> this. Arguments are always evaluated before passed to the function. >> (What one can do, as Jason demonstrated, is pass in a function to be >> evaluated later). > > So, bringing up an issue that has come up before, there is no way > to do > the equivalent of the Hold or HoldAll commands in Mma? See > http://reference.wolfram.com/mathematica/ref/Hold.html?q=Hold&lang=en > for example.
Not without some preparsing magic, and even then it might be tricky as there is not a simple one-to-one correspondence between the python parse tree and the mathematical expression. > It'd still be nice if there were a way to be able to create and deal > with unevaluated symbolic expressions (for example, if I want to print > an integral sign by doing latex(hold(integrate(...))) ). I guess we > could add yet another feature to the preparser if there was enough > demand. > > Another way to do it might be to have classes like Integrate (as > opposed > to functions), that represent an integral. I'm not a fan of making such a distinction based on the capitalization of the first letter, but it would make sense to have integral (the noun) be unevaluated, and integrate (the verb) actually do the work. > That still wouldn't prevent > something like Integral(2+3,(x,0,3)) being simplified to > Integral(5,(x,0,3)), though. No, it wouldn't. - 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 -~----------~----~----~----~------~----~------~--~---
