[newbie] how to expand function to original variables

I have reworked the code as follows:
p(tau11,tau22):=tau11*tau22;
sigma(tau11,tau12,tau22):=tau11+tau12+tau22;
A(p,sigma):=sqrt(p^2+2*p*sigma)-p;
hjmax(A,sigma,p):=sqrt((1+A/p)/((1-A/sigma^2)^2+A/p));
subst(sigma(tau11,tau12,tau22),sigma,hjmax);
subst(p(tau11,tau22),p,hjmax);

this gives me hjmax as a function of tau11, tau12 and tau22 which is what 
I wanted. I just wondered whether the last two statements can be combined 
in one?

thanks for all the help

hugo


On Mon, 18 Feb 2013, Stavros Macrakis wrote:

> As Barton suggests, it's not clear why you've define p and sigma as
> functions, and A and hjmax as expressions.
> If you'd like to keep the unexpanded form in some cases, there are a couple
> of possible approaches:
> 
> * When using the function, don't write just the name (p), but the full call
> p(...), but quote?the call as 'p(...). ?This is what we call a noun form.
> ?It will stay unevaluated until you do ev(<<expr>>, nouns) or more narrowly
> ev(<<expr>>, p).
> 
> * You can also substitute the full value, e.g. subst(p(tau11,tau22), p,
> hjmax).
> 
> ? ? ? ? ? -s
> 
> On Mon, Feb 18, 2013 at 9:11 AM, Barton Willis <willisb at unk.edu> wrote:
>       Since you defined p and sigma to be functions, I think you want
>       something like (append arguments to p and sigma)
>
>       (p(tau11,tau22):=tau11*tau22,
>       sigma(tau11,tau12,tau22):=tau11+tau12+tau22,
> A:sqrt(p(tau11,tau22)^2+2*p(tau11,tau22)*sigma(tau11,tau12,tau22))-p(tau11,
>       tau22),
> hjmax:sqrt((1+A/p(tau11,tau22))/((1-A/sigma(tau11,tau12,tau22)^2)^2+A/p(tau
>       11,tau22))));
>
>       Or maybe you wanted p and sigma to be expressions, not functions
>       ?(thus p : tau11 * tau22, sigma : =tau11+tau12+tau22)?
>
>       --Barton
>
>       ________________________________________
>       From: maxima-bounces at math.utexas.edu
>       [maxima-bounces at math.utexas.edu] on behalf of Hugo Coolens
>       [coolens at kahosl.be]
>       Sent: Monday, February 18, 2013 06:14
>       To: maxima at math.utexas.edu
>       Subject: [newbie] how to expand function to original
>       variables
>
>       I have the following code:
>       p(tau11,tau22):=tau11*tau22;
>       sigma(tau11,tau12,tau22):=tau11+tau12+tau22;
>       A:sqrt(p^2+2*p*sigma)-p;
>       hjmax:sqrt((1+A/p)/((1-A/sigma^2)^2+A/p));
>
>       I now would like to see hjmax written again as a function of
>       tau11, tau12,
>       tau22.
>       Can anyone here point me to which command to use for that
>       purpose?
>
>       thanks in advance
>       hugo
>
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