The inconsistency of polyfit function
1 vue (au cours des 30 derniers jours)
Afficher commentaires plus anciens
x=[1,2,3,4,5];
y=3*x.^2+7*x+12;
p1=plifit(x,y,2);
[p2,S]=polyfit(x,y,2);
[p3,S,mu]=polyfit(x,y,2);
p1
p2
p3
Why p3 not same as p2 and p1
0 commentaires
Réponses (1)
Stephan
le 8 Oct 2019
From the documentation:
[p,S,mu] = polyfit(x,y,n) also returns mu, which is a two-element vector with centering and scaling values. mu(1) is mean(x), and mu(2) is std(x). Using these values, polyfit centers x at zero and scales it to have unit standard deviation.
also in the related example:
Use polyfit with three outputs to fit a 5th-degree polynomial using centering and scaling, which improves the numerical properties of the problem. polyfit centers the data in year at 0 and scales it to have a standard deviation of 1, which avoids an ill-conditioned Vandermonde matrix in the fit calculation.
0 commentaires
Voir également
Catégories
En savoir plus sur Creating and Concatenating Matrices dans Help Center et File Exchange
Produits
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!