Question: How to write data of multiple 2D plots into one file with different columns

Dear all, 

Yesterday I asked a very similar question, but i thought about it and found a different way to re-phrase my question:

Given a plot with three dependent variables that depend on one independent variable, how can I extract this data into a .xls (or .dat or whatever) file for re-use in Maple later on? The .xls will have to have 4 columns: the first for the independent variable and the next three for the dependent variables.

Find my worksheet here: worksheet.mw

I managed to write a program that extracts the data into a .dat file, but with only two columns. 

The reason that I want to do this is because I want to re-use the solutions to the variables and the derivatives in a different equation (for plotting). For example q(z) = ( diff(h1(z),z)+ diff(h2(z),z)+ diff(h3(z),z))/(h1(z) +h2(z) +h3(z)), and then z versus plot q(z). Any alternative suggestions would be helpful.