## [d4a496]: inst / triang.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``` ```## Copyright (C) 2000-2002 Paul Kienzle ## ## 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{w} =} triang (@var{m}) ## ## Returns the filter coefficients of a triangular window of length @var{m}. ## Unlike the bartlett window, triang does not go to zero at the edges ## of the window. For odd @var{m}, @code{triang(@var{m})} is equal to ## @code{bartlett(@var{m}+2)} except for the zeros at the edges of the window. ## @end deftypefn function w = triang(m) if (nargin != 1) print_usage; elseif (!isscalar(m) || m != fix (m) || m < 1) error("triang: M has to be an integer > 0"); endif w = 1 - abs ([-(m-1):2:(m-1)]' / (m+rem(m,2))); endfunction %!error triang %!error triang(1,2) %!error triang([1,2]); %!assert (triang(1), 1) %!assert (triang(2), [1; 1]/2) %!assert (triang(3), [1; 2; 1]/2); %!assert (triang(4), [1; 3; 3; 1]/4); %!test %! x = bartlett(5); %! assert (triang(3), x(2:4)); %!demo %! subplot(221); %! n=7; k=(n-1)/2; t=[-k:0.1:k]/(k+1); %! plot(t,1-abs(t),";continuous;",[-k:k]/(k+1),triang(n),"g*;discrete;"); %! axis([-1, 1, 0, 1.3]); grid("on"); %! title("comparison with continuous for odd n"); %! %! subplot(222); %! n=8; k=(n-1)/2; t=[-k:0.1:k]/(k+1/2); %! plot(t,1+1/n-abs(t),";continuous;",[-k:k]/(k+1/2),triang(n),"g*;discrete;"); %! axis([-1, 1, 0, 1.3]); grid("on"); %! title("note the higher peak for even n"); %! %! subplot(223); %! n=7; %! plot(0:n+1,bartlett(n+2),"g-*;bartlett;",triang(n),"r-+;triang;"); %! axis; grid("off"); %! title("n odd, triang(n)==bartlett(n+2)"); %! %! subplot(224); %! n=8; %! plot(0:n+1,bartlett(n+2),"g-*;bartlett;",triang(n),"r-+;triang;"); %! axis; grid("off"); %! title("n even, triang(n)!=bartlett(n+2)"); ```