Plotting matrices that don't have the same size

I am trying to plot two matrices it doesn't work.

matrix_1 is a 181x1 matrix with different values, I am trying to plot these values and also get a line fitted on the same plot, I tried polyfit as well but it doesn't work.

Message diplayed:

"Error using plot

Vectors must be the same length."

x=1941:2010
y=matrix_1

plot(x,y)

[Matt J]

How would it work? A plot, by definition, is a display of coordinate pairs (xi,yi). If your xi and yi data do not exist in corresponding pairs, what does it mean to "plot" them?

[Bob Thompson]

Yes, matlab is expecting coordinate pairs.

How is your data related? X appears to be years, but should there be one set of results for each year, or is there some other correlation?

[Samy Ben Thabet]

Oh right my bad. I guess I made a mistake somewhere in my code I will try to fix that.

Thank you!

Answer 1

[Ken Atwell]

When calling plot, the length of the x,y pairs must be equal. Here is an example of a plot of x^2 with noise added, then then a polyfit to that data:

x=-3:.1:3;
y=x.^2+rand(size(x));
f=polyfit(x, y, 2); % Returns coefficients, not y values directly
fy = f(1).*x.^2 + f(2).*x + f(3);
plot(x,y,x,fy)

[Akira Agata]

If these two matrices are not the same size but matrix_1 is a sampled data from x = 1941 to 2010 with some fixed sampling frequency, adjusting length of x with linspace function would be possible solution. Here is an example.

x = 1941:2010;
y = matrix_1;

xInterp = linspace(min(x),max(x),numel(y));

figure
plot(xInterp,y)