MathGroup Archive 2008

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Help

  • To: mathgroup at
  • Subject: [mg92301] Re: Help
  • From: "Rui Rojo" <rui.rojo at>
  • Date: Sat, 27 Sep 2008 06:49:14 -0400 (EDT)
  • References: <gbjmbb$3ah$> <>

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]
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> wrote:

> Rui wrote:
>  I'm new in Mathematica. I have version
>> 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?

  • Prev by Date: Re: Help
  • Next by Date: Re: Help
  • Previous by thread: Re: Help
  • Next by thread: Re: Help