Thread Subject:

How to write the Gauss Function VECH in Matlab?

The VECH function in Gauss vectorizes a symmetric matrix by retaining only the lower triangular portion of the matrix. It does in row-wise order.
Example:
x = [11 12 13
       21 22 23
       31 32 33]
therefore,
vech(x) =
[11; 21; 22; 31; 32; 33]

How can I do it in Matlab?

Thanks!

"Patrick" wrote in message <k0kql1$ajs$1@newscl01ah.mathworks.com>...
> The VECH function in Gauss vectorizes a symmetric matrix by retaining only the lower triangular portion of the matrix. It does in row-wise order.
> Example:
> x = [11 12 13
> 21 22 23
> 31 32 33]
> therefore,
> vech(x) =
> [11; 21; 22; 31; 32; 33]
>

y = x';
vech = y(triu(true(size(y))))

% Bruno

Thanks, man! you are good. That works perfectly.