Extracting polynomial coefficients from function handle

I have an unknown large polynomial function handle. for example: f=@(x) 1234*x^2000+654*x^1982+....

I want to extract its coefficients. I know that i Can use a code like this:

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syms y

coefficients=sym2poly(f(y));

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but its too slow beacause i need this to repeat in a loop more than 10000 times.

is there any way to extract coefficient directly from function handle???

Answer 1

[Andrei Bobrov]

reshape(str2double(regexp(func2str(f),'\d*(?=\*x\^)|(?<=\*x\^)\d*','match')),2,[])'

[meysam esmaeeli]

i said that my polynomial function handle is unknown. in fact it is in a form like this:

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 A = @ (x,a1,a2,a3) [x^2+a1,...]

 f = @(x) det (A(x,1,5,6))