Differentiate an inline function
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Hi!
I have an assignment in Matlab and I need to find a function's 8th and 9th derivate. This function is an inline function, as it is an input from the user.
I have been trying to use the function diff, but it tells me: «Function 'diff' is not supported for class 'inline'.»
Any ideas?
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Walter Roberson
el 23 de Nov. de 2012
syms x
f = sym(string_from_input);
diff(f,x,x,x,x,x,x,x,x)
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Matt J
el 23 de Nov. de 2012
Editada: Matt J
el 23 de Nov. de 2012
You cannot do symbolic differentiation on inline functions. If you don't have the Symbolic Toolbox, you will have to either consider a specific family of functions and pre-analyze their derivatives. Or, if you want to do numeric differentiation,
t=linspace(0,T,N);
f = vectorize(inline(string_from_input));
result = diff(f(t),8)./( t(2)-t(1) )^8;
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