Strange output from arange()

[Christopher Barrington-Leigh]

The following code:

    from pylab import arange
    nSegments=5.0
    print arange(0,1.0+1.0/nSegments,1.0/nSegments)
    nSegments=6.0
    print arange(0,1.0+1.0/nSegments,1.0/nSegments)
    nSegments=8.0
    print arange(0,1.0+1.0/nSegments,1.0/nSegments)
    nSegments=10.0
    print arange(0,1.0+1.0/nSegments,1.0/nSegments)

gives an output of:

[ 0.   0.2  0.4  0.6  0.8  1. ]
[ 0.          0.16666667  0.33333333  0.5         0.66666667
0.83333333  1.          1.16666667]
[ 0.     0.125  0.25   0.375  0.5    0.625  0.75   0.875  1.   ]
[ 0.   0.1  0.2  0.3  0.4  0.5  0.6  0.7  0.8  0.9  1. ]

These arrays have lengths, 6, 8, 9, and 11, in stead of 6, 7, 9, and
11.
What is going on for the case of n=6?