Jose - the problem is with the signature of this function
function [output, txtout]=(filepath)
While you are providing the input and output parameter names, you are not supplyinbg a function name. See Declare function name, inputs, and outputs for details on how to do this. In your case, you would do something like
function [output, txtout] = myFunction(filepath)
and save this to a file myFunction.m. This is an example only...you can name it to be whatever you want but the function name must match the file name.
You would then call this function from the command line (or another script or function) as
>> [output, txtout] = myFunction('C:\Users\jgodinez6\Desktop\Read_PTU_V1')
where you pass in the path and name of the function that you want to process. Since you are passing in this string, then this is the value of the filepath input parameter, and so the line to open the file can still remain as
fid=fopen(filepath);
