# [Maxima] how to solve for an implicit derivative --

shorne at energetiq.com shorne at energetiq.com
Tue Oct 21 11:10:48 CDT 2008

```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

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)

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.math.utexas.edu/pipermail/maxima/attachments/20081021/91f877cd/attachment-0001.htm
```