Subject: how to solve for an implicit derivative --
From: shorne at energetiq.com
Date: Tue, 21 Oct 2008 12:10:48 -0400
Sorry all -- that was dumb of me. Works fine.
Thanks --
Steve
"Stavros Macrakis" <macrakis at alum.mit.edu>
Sent by: macrakis at gmail.com
10/21/2008 12:06 PM
To
shorne at energetiq.com
cc
"Maxima List" <maxima at math.utexas.edu>
Subject
Re: [Maxima] how to solve for an implicit derivative --
This seems to work fine for me:
(%i2) depends(y,x);
(%o2) [y(x)]
(%i3) diff(x^2+y^2-1,x);
(%o3) 2*y*'diff(y,x,1)+2*x
(%i4) solve(%,diff(y,x));
(%o4) ['diff(y,x,1) = -x/y]
Is this what you had in mind?
-s
Comments on your code in-line:
On Tue, Oct 21, 2008 at 11:53 AM, <shorne at energetiq.com> wrote:
f(x,y)=0;
depends(y,x);
eq1: diff(f,x);
You need to define f before taking the diff.
And you need to diff an *expression* (e.g. f(x,y)) not a named *function*
(e.g. f).
solve(eq1, dy/dx);
dy/dx is expressed as 'diff(y,x) == diff(y,x)