       Re: arguments of the function

• To: mathgroup at smc.vnet.net
• Subject: [mg35417] Re: arguments of the function
• From: "Allan Hayes" <hay at haystack.demon.co.uk>
• Date: Fri, 12 Jul 2002 04:28:27 -0400 (EDT)
• References: <agjj6h\$255\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

``` In two steps:
args = Sort[Cases[y[t + 3] ==
a1*(Cos[Sin[u[t + 2]]]/Tan[u[t + 1]]) -
Cot[u[t + 3]] + a2, _u, Infinity]]

{u[1+t],u[2+t],u[3+t]}

y[t + 3] == a1*(Cos[Sin[u[t + 2]]]/Tan[u[t + 1]]) -
Cot[u[t + 3]] + a2 /. Thread[args -> {x3, x2, x1}]

y[3+t]==a2-Cot[x1]+a1 Cos[Sin[x2]] Cot[x3]

In one step:

(# /. Thread[Sort[Cases[#, _u, Infinity]] ->
{x3, x1, x2}]) & [y[t + 3] ==
a1*(Cos[Sin[u[t + 2]]]/Tan[u[t + 1]]) -
Cot[u[t + 3]] + a2]

y[3+t]==a2-Cot[x2]+a1 Cos[Sin[x1]] Cot[x3]

--
Allan

---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

"fee eerr" <eleri111 at hot.ee> wrote in message
news:agjj6h\$255\$1 at smc.vnet.net...
> Hi.
> I am using Mathematica 4.0
> I can't find a function that would find arguments of the function.
> For example I have an equation:
> y[t+3]=a1* Cos[Sin[u[t+2]]]/Tan[u[t+1]]-Cot[u[t+3]]+a2
>
> and I would like to get those argumets u[t+3], u[t+2], u[t+1]
> and give them new values
> for example:
>
> x1=u[t+3]
> x2=u[t+2]
> x3=u[t+1]
>
> and then print that equation with new values:
> y[t+3]=a1* Cos[Sin[x2]]/Tan[x3]-Cot[x1]+a2
>
> Can you tell me how to do that?
> Thank you.
>
> -----------------------------------------
> Hot Mobiil - helinad, logod ja piltsõnumid!
> http://www.hot.ee
>

```

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