## [24b7af]: inst / @quaternion / diag.m  Maximize  Restore  History

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 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58``` ```## Copyright (C) 2010-2014 Lukas F. Reichlin ## ## This program 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 3 of the License, or ## (at your option) any later version. ## ## This program 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 this program. If not, see . ## -*- texinfo -*- ## @deftypefn {Function File} {@var{q} =} diag (@var{v}) ## @deftypefnx {Function File} {@var{q} =} diag (@var{v}, @var{k}) ## Return a diagonal quaternion matrix with quaternion vector V on diagonal K. ## The second argument is optional. If it is positive, ## the vector is placed on the K-th super-diagonal. ## If it is negative, it is placed on the -K-th sub-diagonal. ## The default value of K is 0, and the vector is placed ## on the main diagonal. ## Given a matrix argument, instead of a vector, @command{diag} ## extracts the @var{K}-th diagonal of the matrix. ## @end deftypefn ## Author: Lukas Reichlin ## Created: May 2010 ## Version: 0.2 function a = diag (a, b = 0) if (nargin > 2) print_usage (); endif a.w = diag (a.w, b); a.x = diag (a.x, b); a.y = diag (a.y, b); a.z = diag (a.z, b); endfunction %!shared R, S, T, U %! Q = quaternion (2, 3, 4, 5); %! R = diag ([Q, Q, Q]); %! W = diag ([2, 2, 2]); %! X = diag ([3, 3, 3]); %! Y = diag ([4, 4, 4]); %! Z = diag ([5, 5, 5]); %! S = quaternion (W, X, Y, Z); %! T = diag (R); %! U = [Q; Q; Q]; %!assert (R == S); %!assert (T == U); ```