On Jul 25, 3:20 pm, Christopher Barrington-Leigh <[email protected]> wrote: > 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?
It's rounding. See http://docs.scipy.org/doc/numpy/reference/generated/numpy.arange.html stop : number End of interval. The interval does not include this value, except in some cases where step is not an integer and floating point round-off affects the length of out. The stops are 5 -- 1.2 6 -- 1.1666666666666666666666667 8 -- 1.125 10 -- 1.1 Only 6 has to be rounded up. -- http://mail.python.org/mailman/listinfo/python-list
