Filtering

[Hamish Allan]

Hi,

It seems that matrices returned by comparison operators are 'special', 
for example:

octave:1> x = [1 2 3 4 5]
x =

  1  2  3  4  5

octave:2> x > 1
ans =

  0  1  1  1  1

octave:3> x(ans)
ans =

  2  3  4  5

octave:4> ans2 = [0 1 1 1 1]
ans2 =

  0  1  1  1  1

octave:5> x(ans2)
error: invalid vector index = 0
octave:5>

Why is this? How else might I achieve what I want to do, which is:

octave:5> x((x > 1) .* (x < 4))
ans =

  2  3

octave:6>

Many thanks,
Hamish



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