[newbie] how to expand function to original variables

Strange enough reentering the code below the substitution-statements don't 
seem to work any more :-(

hugo


On Tue, 19 Feb 2013, Hugo Coolens wrote:

> 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
>>
>>       _______________________________________________
>>       Maxima mailing list
>>       Maxima at math.utexas.edu
>>       http://www.math.utexas.edu/mailman/listinfo/maxima
>> 
>>
>>       _______________________________________________
>>       Maxima mailing list
>>       Maxima at math.utexas.edu
>>       http://www.math.utexas.edu/mailman/listinfo/maxima
>> 
>> 
>> 
>