Obtaining line equation having multiple points

Hi everyone,is there a way to obtain line equation having multiple points (around seven points) of that line as a 2*7 matrix?

Answer 1

[Star Strider]

The polyfit (and polyval) functions may be what you want.

There are other options, however these are likely the easiest to use.

[Mostafa Moradi]

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]

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.