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function ndx = subv2indKPM(siz, subv)
% SUBV2IND Like the built-in sub2ind, but the subscripts are given as row vectors.
% ind = subv2ind(siz,subv)
%
% siz can be a row or column vector of size d.
% subv should be a collection of N row vectors of size d.
% ind will be of size N * 1.
%
% Example:
% subv = [1 1 1;
% 2 1 1;
% ...
% 2 2 2];
% subv2ind([2 2 2], subv) returns [1 2 ... 8]'
% i.e., the leftmost digit toggles fastest.
%
% See also IND2SUBV.
if isempty(subv)
ndx = [];
return;
end
if isempty(siz)
ndx = 1;
return;
end
[ncases ndims] = size(subv);
%if length(siz) ~= ndims
% error('length of subscript vector and sizes must be equal');
%end
if all(siz==2)
%rbits = subv(:,end:-1:1)-1; % read from right to left, convert to 0s/1s
%ndx = bitv2dec(rbits)+1;
twos = pow2(0:ndims-1);
ndx = ((subv-1) * twos(:)) + 1;
%ndx = sum((subv-1) .* twos(ones(ncases,1), :), 2) + 1; % equivalent to matrix * vector
%ndx = sum((subv-1) .* repmat(twos, ncases, 1), 2) + 1; % much slower than ones
%ndx = ndx(:)';
else
%siz = siz(:)';
cp = [1 cumprod(siz(1:end-1))]';
%ndx = ones(ncases, 1);
%for i = 1:ndims
% ndx = ndx + (subv(:,i)-1)*cp(i);
%end
ndx = (subv-1)*cp + 1;
end
%%%%%%%%%%%
function d = bitv2dec(bits)
% BITV2DEC Convert a bit vector to a decimal integer
% d = butv2dec(bits)
%
% This is just like the built-in bin2dec, except the argument is a vector, not a string.
% If bits is an array, each row will be converted.
[m n] = size(bits);
twos = pow2(n-1:-1:0);
d = sum(bits .* twos(ones(m,1),:),2);
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