wrapinto.m

fading 在无线中的应用

function  wxym = wrapinto(xym, rombvec, type)
% DESCRIPTION wxym = wrapinto(xym, rombvec, type)
%  Matrix xym with complex elements will be wrapped into 
%  a romb that is generated by the two complex elements of 
%  rombvec if type is equal to the string 'romb'.
%  In the same way xym will be wrapped into a hexagon if 
%  type is equal to 'hex'.
% INPUT
%  xym --      Position that should be wraped into the area
%  rombvec --  A vector describing the rhombic area
%  type --     'hex' or 'romb'
% OUTPUT
%  wxym --     New positions in the rhombic area
% TRY  
%  plot(wrapinto(10*irandn(10000,1),exp(i*pi*[0 1]/3),'hex'),'.')
%  axis equal
%  plot(wrapinto(10*irandn(10000,1),exp(i*pi*[0 1]/3),'romb'),'.')
%  axis equal

% by Magnus Almgren 991122

% the inverse base of rombvec. rombvec(1)*base=>[1 0] rombvec(2)*base=>[0 1] 
base = inv([real(rombvec.') imag(rombvec.')]);
rwa = [real(xym(:)) imag(xym(:))];  % first column real part and second imaginary

% wrap it back into the romb 
twa = rwa*base;
wxyv = mod(twa,1)*rombvec.';
%wxyv = (twa - round(twa))*rombvec.';
if strcmp(type,'hex')
 % wrap to shortest distance from origo (possibly a hexagon)
 rwcomb = mplus((-1:1)*rombvec(1),(-1:1)'*rombvec(2));
 wxyv = min(mplus(wxyv,rwcomb(:).'),[],2);
end
wxym = reshape(wxyv,size(xym));