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Re: Derivation with Octave
From: |
Ben Abbott |
Subject: |
Re: Derivation with Octave |
Date: |
Sun, 2 Mar 2008 10:30:46 -0500 |
On Mar 2, 2008, at 8:32 AM, Julien Martin wrote:
Hello,
I am a beginner to Octave and would like to perform derivation on
some functions. Can anyone please help? What is the syntax of the
arguments of the differenciate function?
Thanks in advance,
Julien.
Octave a numerical (not a symbolic) computational tool. If you are
looking for symbolic derivatives, please consider Maxima.
For numerical derivatives, there are many methods to accomplish that
numerically.
Given you have a pair of vectors, x & y, where y is dependent upon x.
dydx = diff (y) ./ diff (x);
xc = x(1:end-1) + diff(x)/2;
dydx = interp1 (x(n), dydx, xc, "linear", "extrap");
If the function, y, may be accurately represented by a polynomial of
order N
dydx = polyval ( polyder ( polyfit (x, y, N)), x);
Ben