Re: Numerical Differentiation and Integration of Array Data

[syberraith]

Actually, I think my central difference algorithm is providing more realistic
answers than Octave's diff function in this case:

n = 400
p = (2 * pi)/200;
h = p / (n-1);
g = h / 2;

function y = f ( x ) 
   y = sin( 200 * x );
endfunction

t = linspace(0 - g, p + g, n + 1);
a = (f(t+g) - f(t-g))/h;
a = h.*(a(1:end-1) + a(2:end))./2;

#t = linspace(0, p, n);
#a = diff(f(t))/h;

s1 = sum(a.*h)
s2 = f(p) - f(0)
ds = s1 - s2  

n = 400
p = (2 * pi)/200;
h = p / (n-1);
g = h / 2;

n = 400
s1 =  1.2398e-06
s2 =  6.4326e-16
ds =  1.2398e-06

Or, am I still missing something?

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