% Count "off" bits in argument: onbits, offbits, parity, paritybits, bits, bit, set
%*************************************************************************************
%
% MATLAB (R) is a trademark of The Mathworks (R) Corporation
%
% Function: offbits
% Filename: offbits.c
% Programmer: James Tursa
% Version: 1.0
% Date: August 4, 2008
% Copyright: (c) 2008 by James Tursa
% Permission: Permission is granted to freely distribute and use this code
% as long as the header information is included.
%
% Important: You don't have to know anything about mex or c to use this
% file! Simply follow the instructions below to build the mex file.
%
% offbits is a mex function that counts the number of "off" bits in variable
% elements. Returns a variable with the same size & structure as the input.
% Fundamental types (double, single, int8, etc) are replaced with a int8
% variable, each element being the number of "off" bits for the corresponding
% input variable element. For structures and cell arrays, each component or
% cell is individually counted. Other classes (e.g., vpa, function handles,
% etc.) are not counted, the return variable is empty. The complex portion
% of variables are counted as well. Can take any number of inputs as long as
% there are matching outputs. Valid variable types for input are:
%
% double
% single
% uint64
% int64
% uint32
% int32
% uint16
% int16
% uint8
% int8
% char
% logical
% cell
% structure
%
% Building:
%
% >> mex -setup
% (then follow instructions to select a C compiler of your choice)
% >> mex offbits.c
%
% Syntax:
%
% Y = offbits(X)
% [Y1 Y2] = offbits(X1,X2)
% [Y1 Y2 Y3] = offbits(X1,X2,X3)
% : :
% etc etc
%
% Note:
%
% For single and double type inputs, offbits counts the actual bits in the
% floating point representation of the number. offbits does *not* count
% the bits in the equivalent integer representation of the number. For
% example:
%
% offbits(int8(-1)) will give a result of 0 (no bits set "off"), whereas
% offbits(-1) will give a result of 53, since that is the number of "off"
% bits in the double floating point representation of -1.
%
%****************************************************************************/
function varargout = offbits(varargin)
disp('Error using offbits: You have not yet generated the offbits mex routine.');
disp('Do the following:');
disp(' ');
disp('>> mex -setup');
disp(' (Then follow instructins to select the C compiler of your choice. (e.g., lcc)');
disp('>> mex offbits.c');
disp(' ');
disp('That''s it! Now you are ready to use offbits.');
error(' ');
end
