Re: Newbie

*To*: mathgroup at smc.vnet.net*Subject*: [mg24493] Re: [mg24490] Newbie*From*: "Mark Harder" <harderm at ucs.orst.edu>*Date*: Thu, 20 Jul 2000 03:01:37 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Dear Want, You describe some very strange behaviour. The correct syntax is D[x^2,x], which on my system (WinNT v.4.0, Mathematica 4.0.1) outputs 2 x, as expected (since Mathematica requires a second argument telling it which symbol is variable, all others in the expression being treated as constants). For D[x^2] by itself and within Print[] my system outputs simply x^2. I can't imagine how enclosing the improperly formed command within Print[] should have any effect on the result. The reason you get no output at all with "D[x^2];" is that following a command with ";" suppresses output, except when the command is an output command, like Print[], or Show[]. The semicolon is used either to suppress output from preliminary calculations, or to separate commands in a compound expression (several expressions taking the place of "expr" in Mathematica's documentation). In the latter case, you *have to* use Print[] or other explicit output commands if you want output from within the body of the compound expression. There are a couple of relatively short books out there for beginners. I suggest you get one and read it, to save yourself a lot of time. -mark e. harder harderm at ucs.orst.edu -----Original Message----- From: WantToKnowPlease <replyNewsGroubPlease at eee.com> To: mathgroup at smc.vnet.net Subject: [mg24493] [mg24490] Newbie >I've just started using mathematica.... >When I type a command and press (shift)+(enter) I don't see any output >unless I preceded the command by print command >D[x^2];(shift)+(enter) doesn't do anything !!(at least I can't see what it >does) >Print[D[x^2]];(shift)+(enter) prints 2 x > > >any help is greatly appreciated > > > >