Store polyfit information of for loop in matrix

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Jerry
Jerry on 12 Apr 2022
Answered: KSSV on 12 Apr 2022
Hi, I have a graph with x = 6309x1 double and y = 6309x1 double.
I want to fit different increasing areas of the graph with polyfit: polyfit area 1-40; polyfit area 1-80; polyfit area 1-120; ........polyfit area 1-6280 (floor(length(x)/40)*40).
These are 157 (floor(length(x)/40)) different areas and I want to store the fitted y-Values in a 157x16280 (not used rows are gonna be replaced by zero)
How can I achieve this in a for loop? I tried the following, but it doesn't work and I cant fit 157 areas manually
yp = zeros(floor(length(xorg)/40)*40,1);
for i = 40:40:length(xorg)
for j = 1:floor(length(xorg)/40)
yp(:,j) = polyval((polyfit(xorg(1:i,1),yorg(1:i,1),9)), xorg(1:i,1));
end
end
  1 Comment
Jan
Jan on 12 Apr 2022
Do you really want the output as 157x16280 or as 6280x157 matrix?

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Answers (2)

Jan
Jan on 12 Apr 2022
Maybe:
n = floor(length(xorg) / 40) * 40;
yp = zeros(n, 1);
for j = 1:floor(length(xorg)/40)
m = j * 40;
yp(:, j) = polyval(polyfit(xorg(1:m), yorg(1:m), 9), xorg(1:m, 1));
end

KSSV
KSSV on 12 Apr 2022
You may save them into a cell as well.
yp = cell(floor(length(xorg)/40)*40,1);
for i = 40:40:length(xorg)
for j = 1:floor(length(xorg)/40)
yp{j} = polyval((polyfit(xorg(1:i,1),yorg(1:i,1),9)), xorg(1:i,1));
end
end

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