Thread Subject: How to reuse the funtion with syms

Firstly, I use x as a syms to discribe a function and want to diff
it. And then, I give x a double value and want to gain value of the
diffed funtion. But I don't know how to reuse the function. Can any
one show me how?
The following is my code.
    syms x
    y =diff(sin(x))
    >>y =cos(x)
Now I want to set x as 2.0 for example, and I want to gain the
value of y without redifining it.

"MingMa" <icesunin@163.com> wrote in message
news:ef5bd45.-1@webcrossing.raydaftYaTP...
> Firstly, I use x as a syms to discribe a function and want to diff
> it. And then, I give x a double value and want to gain value of the
> diffed funtion. But I don't know how to reuse the function. Can any
> one show me how?
> The following is my code.
> syms x
> y =diff(sin(x))
> >>y =cos(x)
> Now I want to set x as 2.0 for example, and I want to gain the
> value of y without redifining it.

If I understand correctly you wish to get the value of y at x=2.0. If that
is true you should try the SUBS function subs(y, x, 2.0). It will return the
value cos(2.0) assuming y is defined as in your example.

Hope that helps,
-Ben