On Mar 19, 7:51 am, PaulBurk <[email protected]> wrote: > Hi all, > > I'm working on a project, and my professor suggest I post a question > here. > > I'm trying to use programs such as Mathematica, Maple and Sage to test > whether a function is always positive. Maple has an "is" command, > which can be used to test some properties. Sometimes it is > sufficient, other times it fails. > > Does Sage have anything like an "is" command? Is there any other way > to test if a function is always positve/negative?
What sort of function? With one argument or multiple arguments? For arbitrary functions (involving trig, exponents, etc.), I'm pretty sure that it's provably impossible to always decide whether a function is always positive, so the best any system can do is apply some heuristics that work for some functions but not others. For univariate or multivariate polynomials (with rational coefficients), it's always possible in theory to determine whether a function is positive everywhere, although I don't know of a method that's usable in practice if there's more than a few variables. Carl --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [email protected] 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 -~----------~----~----~----~------~----~------~--~---
