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I want to plot trend line (and want to record its slop) to multiple figures

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UET Hussain
UET Hussain 2018-2-23
评论： KSSV 2018-2-23
Good Day, I have almost 50,000 points single column data. I divided it into 6 equal parts, calculated rms for each part, and want to plot trending curve of each part. For polyfit, I don't have values of x. I don't know why, but lsline is also not showing anything.
T = 6*fix(numel(V1)/6);
six_parts = reshape(V1(1:T),[],6);
for i = 1:6
sp1= six_parts(:,i);
P1 = sp1;
Pa1 = WinSize*fix(numel(P1)/WinSize); %numel(V1) counts number of elements in V1. it is numeL, not 1(one); fix(A) will round the number to nearest intiger
rP1 = rms(reshape(P1(1:Pa1),WinSize,[]),1);
figure;
% h1 = lsline
plot (rP1);
tmean(i) = trimmean(rP1,10)
xlswrite('abc',tmean);
Any suggestion is welcome
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UET Hussain
UET Hussain 2018-2-23
i tried this, but polyfit is not giving any output..... (means no trend line has been shown)
if true
T = 6*fix(numel(N)/6);
six_parts = reshape(N(1:T),[],6);
for i = 1:6
sp1= six_parts(:,i);
x= 1:length(sp1);
x=x';
P1 = sp1;
Pa1 = WinSize*fix(numel(P1)/WinSize); %numel(V1) counts number of elements in V1. it is numeL, not 1(one); fix(A) will round the number to nearest intiger
rP1 = rms(reshape(P1(1:Pa1),WinSize,[]),1);
figure;
plot (sp1);
polyfit(x,sp1,1);
tmean(i) = trimmean(sp1,10)
xlswrite('abc',tmean);
end
am i putting polyfit at right position????
KSSV
KSSV 2018-2-23
polyfit gives you slope and y-intercept of your straight line.....using these you need to draw you line.....you are not doing that....

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KSSV
KSSV 2018-2-23
Use polyfit like below to draw a line later:
x = linspace(0,4*pi,10);
y = sin(x);
% Use polyfit to fit a line to the points
p = polyfit(x,y,1);
% Evaluate the polynomial on a finer grid and plot the results.
x1 = linspace(0,4*pi);
y1 = polyval(p,x1);
figure
plot(x,y,'o')
hold on
plot(x1,y1)
hold off
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