Re: Help

*To*: mathgroup at smc.vnet.net*Subject*: [mg92301] Re: Help*From*: "Rui Rojo" <rui.rojo at gmail.com>*Date*: Sat, 27 Sep 2008 06:49:14 -0400 (EDT)*References*: <gbjmbb$3ah$1@smc.vnet.net> <48DDBD6E.4080304@gmail.com>

Thanks a lot :) . I'll go on bothering, feel free not to answer, hehe... I'm trying to understand how all this works. If I put in a variable an expression, like expr = 2*x+65-t; then I can't use it in certain situations because mathematica seems to expect to "see" the x and t, but in some others I can. for example expr = 2*x+65-t; Animate[Plot[expr, {x, 0, 4}], {t, 0, 5}]; doesn't work... neither does: ran={x, 0, 4}; Plot[Sin[x], ran] but Clear[expr];expr=2+x;Plot[expr, {x, 0, 4}] does work. In some of the places where it doesn't work, you seem to be able to sort the problem by declaring expr[x_, etc]=etc etc and then using expr[x, etc]... but not all the times... in the case of ran, it doesn't work either. How exactly does all of this work, or where can I read about it? i can't find anything clear in the Help... Is there any way to tell mathematica: "ok, heere replace expr for what you have stored, imagine instead of expr it says what i read when i type expr and press shift+enter"... or how do you think i should manage all this? just guessing, testing and changing? On Sat, Sep 27, 2008 at 1:58 AM, Jean-Marc Gulliet < jeanmarc.gulliet at gmail.com> wrote: > Rui wrote: > > I'm new in Mathematica. I have version 6.0.3.0. >> I'm trying to create an animation or a plot, something simple. I found >> Animate[]. >> I can make it work fine by doing something "like" >> Animate[Plot[Sin[34*x-2*t], {x, 0, 2*pi}], {t, 0, 5} ] >> But if i have my expression stored in a variable i can't... >> a = Sin[34*x-2*t]; >> Animate[Plot[a, {x, 0, 2*pi}], {t, 0, 5} ] >> leaves the animation blank. >> >> I tries all variants I could think of and I always fail. I actually >> wanted to create several animations of expressions i have stored in a >> list, and I could do it one by one manually but I wanted to learn the >> proper way and I'm frustrated already. Any ideas? >> >