How to extract powers of a symbolic polynomial?
31 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
I'm working with a symbolic polynomial
y = 0.96*z^3500 + 0.04*z^0
I can extract the coefficients easily with
coeffs(y)
but I cannot figure out a way to pull off the corresponding powers of z into a vector. I've tried doing some wonky stuff with logs, but nothing so far. Am I SOL?
Thank you!!
0 Commenti
Risposte (3)
Steven Lord
il 22 Mar 2021
syms z
y = 0.96*z^3500 + 0.04*z^0
[coefficients, powers] = coeffs(y)
syms y positive
exponents = simplify(subs(log(powers)./log(z), z, y))
1 Commento
Walter Roberson
il 19 Lug 2021
Different formulation for finding the exponents.
syms z
y = 0.96*z^randi(9999) + 0.04*z^randi(9999)
[coefficients, powers] = coeffs(y)
exponents = mapSymType(powers, 'power', @(Z) children(Z,2));
if powers(end) == 1; exponents(end) = 0; end
exponents
This particular code relies on an enhancement to children() that was made a small number of releases ago. A workaround is possible for older releases.
Shubham Rawat
il 22 Mar 2021
Hi Alina,
You may first find coefficients of all variables like this:
coef = sym2poly(y);
Then you can find all the index of all the non zero elements and -1 as indexing start from 1 in MATLAB:
polyPowers = find(coef) - 1;
Hope this Helps!
1 Commento
Davy Figaro
il 19 Lug 2021
This is good, but because symbolic polynomial powers are presented in descending order, you need to double flip to get the polyPowers to line up to the original polynomial:
polyPowers = flip(find(flip(coef))) - 1;
Vedere anche
Categorie
Scopri di più su Calculus in Help Center e File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!