It is possible to use 'polyval' with data containing nan?

Hi, I want to plot the trend line of 'fice'(856x1), but it has 'nan' from 1:214. When I use 'polyval' the function does not plot the trend line, because it has 'nan's' ...

If I manually put the trend line using 'Tools>Basic Fitting' I can plot the trend line, but it starts from '1' and I want it to start from the '215'

Does anyone have an idea to help me? thanks :)

this is my code...

figure;

aa=[1:(214*4)];

plot(aa',fice,'c');

hold on ;

my_poly=polyfit(aa',fice,1);

X2=215:856; % X data range

Y2=polyval(my_poly,X2);

plot(X2,Y2,'r');%trend line

hold on

plot(Dib,'b'); %plot das áreas normais

hold off

PS: sorry if I have English errors

Answer 1

[Walter Roberson]

mask = isnan(fice);
t_aa = aa(~mask);
t_fice = fice(~mask);
my_poly = polyfit(t_aa, t_fice, 1);

[Camila Hashimoto]

hey, you are the best! thanks ;)