newbie | implicit differentiation



  Thanks very much -- I'll give that a try. Wrapping it into a function 
is probably a good idea (for class, I prefer to render things in single 
functions calls as much as is possible).

On 10/14/2010 1:42 PM, Joshua Stults wrote:
> On Thu, Oct 14, 2010 at 12:35 PM, egc<cooch17 at verizon.net>  wrote:
>> f:=lamda^2-lambda*c-a*lambda+a*c-b^2=0
>> To implicitly differentiate lambda with respect to  in Maple, I'd simply
>> enter
>> implicitdiff(f,lambda,c)
>> yielding
>>   (a-lambda)/(-2lambda+c+a)
>> There is no straight equivalent in Maxima for the implicitdiff command in
>> Maple (not that I can find).
> I don't know of one either.
>
>> So, how does one do simple implicit differentiation in Maxima? Is there a
>> simple 'single command' to do the trick, or do I have to break up the
>> problem in pieces, somehow?
> This seems to do what you want:
>    depends(lambda, c);
>    f : lambda^2 - lambda*c - a*lambda + a*c - b^2 = 0;
>    foo : diff(f, c);
>    fim : solve(foo, diff(lambda, c))[1]; /* solve returns a list of
> solutions, but there's just one in this case */
>
> If you want just the right-hand side of the result in an expression,
> that's just:
>    just_rhs_expr : rhs(fim);
>
> I suppose you could wrap that in a little Maxima function for your
> students if you wanted.
>
> Happy Maxima'ing!
>