Thanks Walter.
This is a very nice trick!!!
I think we've hit a bug. This code mis behaves (becouse the combination with symbolic expressions), giving an unreal big number of low significant decimals:
syms a b c d real
[[a,a+b,c-d]', vpa([1,2,3.1234]',3)]
While
syms a b c d real
[[a,a+b,c-d]', vpa(round([1,2,3.1234]',3))]
runs just OK.
Thanks a lot!!!.