mt = fmodtime(flist, year_base )
This function gets the modification time of all specified files on the command line.
Array of file names with path if not in current directory. One can use strvcat on the file names to create this list.
Base year for decimal day conversions.
Array of decimal days corresponding to the modification times (relative to year_base) of each of the files in flist. If a file does not exist,or is multiple,its modification time is set to NaN.
Pierre Jaccard, Geophysical Institute, University of Bergen, 1999