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Asked by Giorgos Papakonstantinou
on 13 May 2013

I want to differentiate a function f and the calculate the derivative of f at value of x. How can I do that? for example:

syms x

f=@(x) x^3+3*x+1;

g=diff(f(x))

Preferably I would like to create a function handle of the derivative and then calculate the derivative at x.

Answer by Sean de Wolski
on 13 May 2013

Accepted answer

Almost there!

gfun = matlabFunction(g) g(2)

Sean de Wolski
on 13 May 2013

Rule #1 of Answers: if you rewrite something from MATLAB, you will make a typo :)

Answer by Iman Ansari
on 13 May 2013

Hi.

syms x f=@(x) x^3+3*x+1; g=diff(f(x)) h=@(y) subs(g,y)

Giorgos Papakonstantinou
on 13 May 2013

Thank you! But then if I ask for g(2) then I get this error:

Error using mupadmex Error in MuPAD command: Index exceeds matrix dimensions.

Error in sym/subsref (line 1389) B = mupadmex('symobj::subsref',A.s,inds{:});

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