Re: Help

• To: mathgroup at smc.vnet.net
• Subject: [mg92302] Re: Help
• From: "Rui Rojo" <rui.rojo at gmail.com>
• Date: Sat, 27 Sep 2008 06:49:26 -0400 (EDT)
• References: <gbjmbb\$3ah\$1@smc.vnet.net> <48DDBD6E.4080304@gmail.com>

```Or, for example, now I wanted to create a wave pack, adding up different
waves...
so i put in a for loop something like
Onda+= Sin[blabla]
now I have my wave pack stored in Onda, but I want to make it a function and
I can't... If I do f[x_, t_]:=Onda
it doesn't work :S

On Sat, Sep 27, 2008 at 2:46 AM, Rui Rojo <rui.rojo at gmail.com> wrote:

> 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?
>>>
>>
>

```

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