From help-octave-request at bevo dot che dot wisc dot edu Fri Oct 24 15:34:01 2003
Subject: Index expressions, boolean types and numerical types
From: Greg Novak <novak at ucolick dot org>
To: help-octave at bevo dot che dot wisc dot edu
Date: Fri, 24 Oct 2003 15:30:13 -0500

Does Octave have boolean types?  Does it keep track of them silently?  How 
do you do casts between numerical types and boolean types?  If there are 
no boolean types, then how does the following fragment of a session make 
sense?

octave:68> y=1:10
y = 1   2   3   4   5   6   7   8   9  10
octave:69> y(y<11)
ans = 1   2   3   4   5   6   7   8   9  10
octave:70> k=y<11
k = 1  1  1  1  1  1  1  1  1  1
octave:71> y(k)
ans = 1   2   3   4   5   6   7   8   9  10
octave:72> k=ones(1,10)
k = 1  1  1  1  1  1  1  1  1  1 
octave:73> y(k)
ans = 1  1  1  1  1  1  1  1  1  1 
octave:74>

k looks exactly the same when I assign it by k=y<11 or k=ones(1,10), but 
the behavior of y(k) is very different in the two cases.

What gives?
Thanks,
Greg



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