## plotting a second derivative graph ...

I can't seem to plot the second derivative graph for f'' versus y. Is it possible to use the fdiff command twice in a line?

Open to all opinions. Any help would be greatly appreciated :)

fyp3.mw

## what happen with this numerical differentiation of...

 (1)

 (2)

 (3)

 (4)

when i try to get a numerical solution(using fdiff) for a second order derivative from a numerical diff ecuation procedure i got "index out of range". however, it perfectly works with a first order derivative. what's thwe matter there?

thankyou very much..

## How to obtain the derivative value of a function o...

I have the following code in Maple 13:

SYS := {diff(T(x, t), t) = diff(T(x, t), x, x)};
IBC := {T(1, t) = 0, T(x, 0) = 1, (D[1](T))(0, t) = -exp(t)};
SOL := pdsolve(SYS, IBC, numeric, time = t, timestep = 1/10);
R := SOL:-value(output = listprocedure); temperature := subs(R, T(x, t));

It integrates the heat equation in the interval x=0..1 and it seems to work ok.
However, I have problems trying to obtain the temperature derivative at the boundaries (this is at x=0 and x=1). I'm using different commands and it seems the derivative is evaluated ok inside the domain but not at the boundaries.
If I try
fdiff(temperature(x, t), [x], {x = 1,t=0.5});

or

evalf((D[1](temperature))(1, .5));

I don't get any numerical answer. Any idea how I could obtain the value of the derivative at the boundaries?

Javier