Comments on: MATLAB Basics video: Solving linear equations

By: Doug

Doug — Fri, 30 Jan 2009 18:04:35 +0000

What are the dimensions of A and y once they are constructed?

I suspect that they are

A = 2×2
y = 2×1

If that is the case,
x = 2×1

That is expected.

Doug

By: Sébastien

Sébastien — Fri, 30 Jan 2009 17:16:39 +0000

Well, that’s what I tried:
Let’s say that y=A*x
In my case, I have:

A=[gamma2(:,1),gamma3(:,1);vega2(:,1),vega3(:,1)];
y=[gamma(:,1);vega(:,1)];
x=A\y;
But with that code x has only two values, and I want x to be a vector. Do you see my problem? Thanks a lot

By: Doug

Doug — Fri, 30 Jan 2009 16:38:09 +0000

Sebastien,

You will want to store those coefficients into a dedicated matrix. You will have to use subscripting to get them into the matrix from those vectors.

Doug

By: Sébastien

Sébastien — Fri, 30 Jan 2009 15:16:57 +0000

Hi,

I understood your video, but how to do it if the coefficients of the equations are vectors? For example, if I have:

gamma1(:,1)= nc2(:,1)*gamma2(:,1)+nc3(:,1)*gamma3(:,1)
vega1(:,1)=nc2(:,1)*vega2(:,1)+nc3(:,1)*vega3(:,1)

and I want to find nc2 and nc3?

Thanks a lot!