%---------------------------------------------
%
% For A321 course
%
%  Started: Mon 16 Feb 2009, 02:28 PM
%  Last Modified: Mon 16 Feb 2009, 03:34 PM
%---------------------------------------------
%
% 
% Matlab can combine or negate relational expressions giving 
% true/false values using the standard logical Boolean operators
% and, not, or.  Those operators have the following symbols:
% 
% ----------------    ------ 
% Boolean operator    symbol 
% ----------------    ------ 
%      and              &
%      or               |
%      not              ~
% 
% Those follow the usual Boolean rules:
% 
%--------------------------
%     true  & true  = true
%     false & true  = false
%     true  & false = false
%     false & false = false
% 
%     true  | true  = true
%     false | true  = true
%     true  | false = true
%     false | false = false
% 
%     ~ true  = false
%     ~ false = true
%--------------------------
%
%---------------------------------------------------------------------

echo on;
%------------------------------------------------------------------
% Notice that "true" is represented by (almost) any nonzero value, 
% not just by 1. What happens if some component of a is set to NaN?
%------------------------------------------------------------------
a = -3:5

not_a = ~a

%---------------------------------------------------------------------
% Since true and false are represented in Matlab by 1 and 0, it can
% be confusing at times whether an integer/double or boolean is meant.
% I recommend you initialize any logical/Boolean variable to be
% true or false rather than 1 and 0. Viz., 
%---------------------------------------------------------------------
b = true;

%----------------------------------------------------------
% See what happens to the type of variable for a, not_a, b.
%----------------------------------------------------------
whos

%-----------------------------------------------------------
% Warning: there are also doubled up logical operators, e.g.
%-----------------------------------------------------------

disp('Using && on the first element of b and not_a gives ');
c(1) = not_a(1) && b(1)

%--------------------------------------------------------------
% Those are for bit-by-bit negation, not at the level of bytes.
% Try to run the && statement above for an entire vectors.
% Just remove the (1) wherever it appears.
%--------------------------------------------------------------
disp('Hit return to see effect of using && on the the entire vectors b and not_a ');
pause;
c = not_a && b

echo off;