-bash-4.2$ ./ptrtest2 data1.txt 12 3
Processing first 12 values from data1.txt.
first 6 values:
    406.94    198.63    961.99
    238.36    910.21    188.81
last 6 values:
    188.81    467.37    639.60
    125.10    581.16    144.50
all values in sorted order:
    125.10    144.50    188.81
    198.63    238.36    354.07
    406.94    467.37    581.16
    639.60    910.21    961.99
-bash-4.2$ ./ptrtest2 data1.txt 25 5
Processing first 25 values from data1.txt.
first 12 values:
    406.94    198.63    961.99    238.36    910.21
    188.81    467.37    639.60    125.10    581.16
    144.50    354.07
last 13 values:
    812.45    716.26    150.35    753.40    387.70
    491.69    788.64    624.17    263.02    545.16
    908.81    829.42    620.95
all values in sorted order:
    125.10    144.50    150.35    188.81    198.63
    238.36    263.02    354.07    387.70    406.94
    467.37    491.69    545.16    581.16    620.95
    624.17    639.60    716.26    753.40    788.64
    812.45    829.42    908.81    910.21    961.99