Reading multiple variables in workspace named sequentially and writing to text file.

Hi, I have data with six columns and I would like to read them in a loop, perform the row index given by;

    row_idx = (hr == M(:, 2) & -40 <= M(:, 3) & M(:, 3) <= 0 ...
            & 135 <= M(:, 4) & M(:, 4) <= 180 | (-180 < M(:, 4) ...
            & M(:, 4) <= -120));

    filtered_M = M(row_idx, :).

where M is a dummy variable which has been assigned value of a variable, and hr is the hour (which I will already assign as a global variable).

The variables are named as A(year)(month)(day) eg, A20130101 for data of 1st January 2013.

I would like to read the variables, perform the row index, and write the number to rows in resulting matrices into a text file.

I have difficulty reading the variables and then writing the number of rows in the resulting matrices in a text file.

[Geoff Hayes]

Ashneel - what difficulty are you experiencing in reading the variables? What code have you written so far?