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Thread Subject: symbolic partials

Subject: symbolic partials

From: Steve

Date: 14 Oct, 2007 21:30:31

Message: 1 of 1

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Ahh, yes, you are correct. However, I was not complete in
the description of the problem. What I'm looking for is
how to take partials with respect to symbols that are
functions of time.

syms x y
x=sym('x(t)')
y=sym('y(t)')
f=x*y
diff(f,x)=error

I need the symbols to be functions of time so I can
differentiate, etc. in previous steps. Is there a way to
do this without converting all symbols that are functions
of time back to simply their variables?

Thanks,
Steve

dsv <deflagrator@gmail.com> wrote in message
<1192227295.371965.273400@q5g2000prf.googlegroups.com>...
> I seem to be able to differentiate perfectly fine. I am
running Matlab
> 2006Rb.
>
> syms x y
> f=x*y;
> diff(f,x)
>
> ans =
>
> y
>
> -dsv
>
> On Oct 12, 4:36 pm, "Steve "
<steveDEL.bachmeier...@yahoo.com> wrote:
> > Oops, I meant that diff(f,'x') gives me zero. So,
> >
> > f=x*y
> > diff(f,'x')
> > ans=0
> >
> > I'm looking for
> > ans=y
> >
> > Ideas?
> >
>

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