polyfit in a for loop
4 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
I want to perform a polyfit in a for loop
for n=1:270
slopex(n) = polyfit(cos(n^3), 3*n, 1)
end
I want to store only the 270 slope values in the vector "slopex"
thanks!
0 Commenti
Risposta accettata
Greig
il 22 Feb 2015
Firstly, this is a poorly conditioned problem. You are trying to fit a straight line through a single data point, so there is no unique solution.
I guess you are wanting the slope to pass through the origin? If so, and since you are then only fitting to two points, you want to use
polyfit([0, cos(n^3)], [0, 3*n], 1)
So following the loop approach, you want to use something like..
for n=1:270
Data_Fits(n,:) = polyfit([0, cos(n^3)], [0, 3*n], 1);
end
slopex=Data_Fits(:,1);
This can be done without the loop, but this only works for the simple case of passing through the origin...
n=1:270;
slopex=(3.*n)./cos(n.^3);
As a point of note, n ranges up to 270, which looks to me to be an angle in degrees? If so, you should note that cos() assumes radians, so you should use cosd() instead, or convert n to radians. Of course, if this is not what you're doing, you can completely ignore this last point.
2 Commenti
Greig
il 22 Feb 2015
Please note, that without the extra zeros in the data when you call polyfit, the results will be meaningless.
Più risposte (0)
Vedere anche
Categorie
Scopri di più su Matrix Indexing in Help Center e File Exchange
Prodotti
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!