Error using * Inner matrix dimensions must agree - using meshplot

1 view (last 30 days)
I have been trying to draw the direction fields of some first order differential equations and sometimes I can get it to work, others not.
This is an example of a problem I have just had:
To sketch the direction field of dy/dt - 2*y = t^2 . e^(2t)
I have tried the following:
>> [t y]=meshgrid(0:0.5:2,-4:0.5:4); >> dy=t.^2*exp(2.*t)+2.*y;
But an it immediately states there is an error: Error using * Inner matrix dimensions must agree.
I can't see what the problem is because in other instances this error does not occur. For example, this worked perfectly:
>> [t y]=meshgrid(-4:0.5:4,-4:0.5:4); >> dy=t - 3*y +exp(-2*t); >> dt=ones(size(dy)); >> L=sqrt(1+dy.^2); >> quiver (t, y, dt./L, dy./L, 0.5), axis tight;

Accepted Answer

Mischa Kim
Mischa Kim on 4 Mar 2014
Edited: Mischa Kim on 4 Mar 2014
Will, use
[t y] = meshgrid(0:0.5:2,-4:0.5:4);
dy = t.^2.*exp(2*t) + 2.*y; % need to use dot operators all the way
dt = ones(size(dy));
L = sqrt(1 + dy.^2);
quiver (t, y, dt./L, dy./L, 0.5)
axis tight;

More Answers (0)

Categories

Find more on Matrices and Arrays in Help Center and File Exchange

Products

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!