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sortcom.m
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1999-04-29
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# Copyright (C) 1996 A. Scottedward Hodel
#
# This file is part of Octave.
#
# Octave is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2, or (at your option) any
# later version.
#
# Octave is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License
# along with Octave; see the file COPYING. If not, write to the Free
# Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
function [yy,idx] = sortcom(xx,opt)
# [yy,idx] = sortcom(xx[,opt]): sort a complex vector
# xx: complex vector
# opt: sorting option:
# "re": real part (default)
# "mag": by magnitude
# "im": by imaginary part
#
# if opt != "im" then values with common real part/magnitude are
# sorted by imaginary part, i.e. a - jb followed by a + jb.
# [Complex conjugate pairs may not be grouped consecutively if more than 2
# numbers share a common real part/magnitude]
# yy: sorted values
# idx: permutation vector: yy = xx(idx)
# Written by A. S. Hodel June 1995
if( nargin < 1 | nargin > 2 )
usage("yy = sortcom(xx[,opt]");
elseif( !(is_vec(xx) | isempty(xx) ))
error("sortcom: first argument must be a vector");
endif
if(nargin == 1) opt = "re";
else
if (!isstr(opt))
error("sortcom: second argument must be a string");
endif
endif
if(isempty(xx))
yy = idx = [];
else
if(strcmp(opt,"re")) datavec = real(xx);
elseif(strcmp(opt,"im")) datavec = imag(xx);
elseif(strcmp(opt,"mag")) datavec = abs(xx);
else error(["sortcom: illegal option = ", opt])
endif
[datavec,idx] = sort(datavec);
yy= xx(idx);
if(strcmp(opt,"re") | strcmp(opt,"mag"))
# sort so that complex conjugate pairs appear together
ddiff = diff(datavec);
zidx = find(ddiff == 0);
# sort common datavec values
if(!isempty(zidx))
for iv=crt_set(datavec(zidx))
vidx = find(datavec == iv);
[vals,imidx] = sort(imag(yy(vidx)));
yy(vidx) = yy(vidx(imidx));
idx(vidx) = idx(vidx(imidx));
endfor
endif
endif
endif
endfunction