How to calculate the mode of a series in Fortran

How can I calculate the mode of a series using Fortran?

For example:

1,2,2,3,3,3,4,4,5
Mode = 3

If your numbers are sorted (as they appear to be), the pseudo-code is simple:

set maxval to -1
set maxcount to -1
set count to -1
set lastval to list[0] - 1
for every val in list:
    if val is not equal to lastval:
        if count is greater than maxcount:
            set maxval to lastval
            set maxcount to count
        set count to 0
        set lastval to val
    set count to count plus one
if maxcount is not equal to -1:
    print "mode is " maxval " with count of " maxcount

Keep in mind that this will return only the first mode if there is more than one.

You can find already made code out there, if you need it and it is not just an exercize; e.g. Mode at wiki rosettacode.org. If it is an exercize, try first to follow the algorithm given in the other answer.