A general example of how a main program and functions should be set up
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process_data.m		main program

fcalcQ.m			custom functions called by main program
fread1col.m
fwrite1col.m

datafile1.dat		input data
datafile2.dat

y.dat				output data (generated by process_data.m)


NB all files must be in same directory, so matlab knows where to find things.
(Alternatively, place *.m files in your 'programs' directory.)

To run in matlab
>> process_data