Finding distinct values in a column of a matrix

I have a 81*4 matrix. I want to find the distinct values only in the first column, which can also be seen as the first column of every row.

eg: a= 2 3

     4 3

     4 5

     2 3

ans should be = 2

            4

unique() is of no use here, it supports only whole row distinction.

Answer 1

[Walter Roberson]

unique( a(:,1) )

[Abdulaziz Abutunis]

Hi Walter,

I hope you are well.

Can we maintain full arrays corresponding to these unique vlaues

Thanks

Aziz