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(a) if the current x is lower than the previous x:
    (a.1) if the current x has been seen before, discard the current p
+oint
    (a.2) else discard the previous point.
(b) elsif the current x is identical to the prev. x (due to a.1 on pre
+v.iteration)
    (b.1) discard previous point

#! perl -slw
use strict;
...
}

print join ' ', @$_ for @modified;

0.0036759 0.4018006     0.0036759 0.4018006
0.0036962 0.4074616     0.0036962 0.4074616
...
0.0041239 0.8591068     0.0041239 0.8591068
0.0041341 0.864785 
0.0041443 0.8760895     0.0041443 0.8760895