Re: Unexpected "Invalid comparison" error when plotting function defined with a Condition pattern

*To*: mathgroup at smc.vnet.net*Subject*: [mg69175] Re: Unexpected "Invalid comparison" error when plotting function defined with a Condition pattern*From*: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>*Date*: Fri, 1 Sep 2006 06:40:24 -0400 (EDT)*Organization*: Uni Leipzig*References*: <ed68td$jgk$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, just read the error message -- 10^y gaves a small imaginary part and g[x_?NumericQ /; 0 < Chop[x]] := x will fix the problem. Regards Jens "Andrew Moylan" <andrew.j.moylan at gmail.com> schrieb im Newsbeitrag news:ed68td$jgk$1 at smc.vnet.net... | Hi, | | Please consider the following simple function, defined for positive x | using a Condition pattern: | | g[x_ /; 0 < x] = x; | | When I try to plot this function in the following way: | | Plot[Abs[g[10^y]], {y, 1, 2}]; | | I unexpectedly receive some "Less::nord : Invalid comparison with 10. + | 0. I attempted" errors. Can anyone explain why this is, and how I | should best prevent it? | | Relevant note: | Both of the following different plots of g succeed with no errors: | Plot[Abs[g[y]], {y, 1, 2}]; | Plot[g[10^y], {y, 1, 2}]; | | Irrelevant note: | In my actual application, the function g is more complicated and is | complex-valued (hence my use of Abs); but the error is reproducable | with the very simple real-valued function g as defined above. | | Thanks for any insight you might be able to give me on this. | | Cheers, | | Andrew |