## [0404a4]: inst / @galois / conv.m  Maximize  Restore  History

 ``` 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 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81``` ```## Copyright (C) 2002 David Bateman ## ## 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} {} conv (@var{a}, @var{b}) ## Convolve two Galois vectors. ## ## @code{y = conv (a, b)} returns a vector of length equal to ## @code{length (a) + length (b) - 1}. ## If @var{a} and @var{b} are polynomial coefficient vectors, @code{conv} ## returns the coefficients of the product polynomial. ## @seealso{deconv} ## @end deftypefn function y = conv (a, b) if (nargin != 2) print_usage (); endif if (!isgalois (a) && !isgalois (b)) error("conv: at least one argument must be a galois variable"); elseif (!isgalois (a)) a = gf(a, b.m, b.prim_poly); elseif (!isgalois (b)) b = gf(b, a.m, a.prim_poly); elseif (a.m != b.m && a.prim_poly != b.prim_poly) error("conv: both vectors must be in the same galois field"); endif if (min(size(a)) > 1 || min(size(b)) > 1) error("conv: both arguments must be vectors"); endif la = length (a); lb = length (b); ly = la + lb - 1; ## Ensure that both vectors are row vectors. if (rows (a) > 1) a = reshape (a, 1, la); endif if (rows (b) > 1) b = reshape (b, 1, lb); endif ## Use the shortest vector as the coefficent vector to filter. if (la < lb) if (ly > lb) ## Can't concatenate galois variables like this yet ## x = [b, (zeros (1, ly - lb))]; x = gf([b, (zeros (1, ly - lb))], b.m, b.prim_poly); else x = b; endif y = filter (a, 1, x); else if(ly > la) ## Can't concatenate galois variables like this yet ## x = [a, (zeros (1, ly - la))]; x = gf([a, (zeros (1, ly - la))], a.m, a.prim_poly); else x = a; endif y = filter (b, 1, x); endif endfunction ```