[0] Perl> print fmod( $_, 100 ) for 12300, 12301, 12399, .00001;;
0
1
99
1e-005

##</code><code>##

[0] Perl> print fmod( $_, 1 ) for map{ ($_, -$_ ) } 12300, 12301, 12399, .00001;;
0
0
0
0
0
0
1e-005
-1e-005