polyfit returns NaN values in p
77 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
florence briton
am 18 Mai 2015
Kommentiert: Steven Lord
am 9 Dez. 2015
I want to do a linear regression on the response Y (attached)with a predictor vector X. Therefore, I used Matlab polyfit function: [p,s,mu]=polyfit(X,Y,1) but it returns p=[NaN,Inf]
I have Inf values in vector Y. Is it the cause?
0 Kommentare
Akzeptierte Antwort
John D'Errico
am 18 Mai 2015
Bearbeitet: John D'Errico
am 18 Mai 2015
Yes. infs in your data will surely cause NaNs, and essentially garbage results. Drop them out first if you expect something meaningful.
y = [rand(10,1);inf];
x = rand(11,1);
p = polyfit(x,y,1)
p =
NaN Inf
Surely you don't expect anything reasonable to come out of such a computation with INFs in it. What would the slope of such a line be with some data points at infinity? Of course, any such point at infinity would have infinite leverage.
0 Kommentare
Weitere Antworten (1)
carlo lefevre
am 9 Dez. 2015
ind = 1:length(a); k = ~isnan(a); p = polyfit(ind(k),a(k),n)
1 Kommentar
Steven Lord
am 9 Dez. 2015
You probably want to use ISFINITE instead of ~ISNAN to include only finite values (excluding Inf, -Inf, and NaN) rather than including only non-NaN values (which would NOT exclude Inf or -Inf.)
Siehe auch
Kategorien
Mehr zu Logical finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!