Obtaining line equation having multiple points

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Mostafa Moradi
Mostafa Moradi 2021-2-28
评论： Star Strider 2021-2-28
Hi everyone,is there a way to obtain line equation having multiple points (around seven points) of that line as a 2*7 matrix?

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回答（1 个）

Star Strider
Star Strider 2021-2-28
The polyfit (and polyval) functions may be what you want.
There are other options, however these are likely the easiest to use.
  2 个评论
Mostafa Moradi
Mostafa Moradi 2021-2-28
this is the data set I have,
y= [0 1 3 5 7 8 9 10]; %distance from sea bank
H= [0 1 1.5 3 3.5 3.2 2 0]; %depth
u= [0 0.1 0.12 0.2 0.25 0.3 0.15 0]; %velocity
how do I apply the above function to get the (y,H) and (y,u) lines equation?
Star Strider
Star Strider 2021-2-28
Try this:
y = [0 1 3 5 7 8 9 10]; %distance from sea bank
H = [0 1 1.5 3 3.5 3.2 2 0]; %depth
u = [0 0.1 0.12 0.2 0.25 0.3 0.15 0]; %velocity
ByH = polyfit(y,H,1);
fit_yH = polyval(ByH,y);
Byu = polyfit(y,u,1);
fit_yu = polyval(Byu,y);
figure
plot(y, H, 'pb')
hold on
plot(y, u, 'pg')
plot(y, fit_yH, '-b')
plot(y, fit_yu, '-g')
hold off
grid
xlabel('y')
ylabel('Amplitude')
legend('H','u','Fit_H','Fit_u', 'Location','NW')
These will provied a linear fit to both dependent data vectors with respect to ‘y’. For polynomial fits of greater (integer) degrees, see the documentation I linked to earlier.
Change other parts of my code to get the results you want.

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