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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) ????-2008 - INRIA
// Copyright (C) 2010 - DIGITEO - Allan CORNET
//
// This file is released under the 3-clause BSD license. See COPYING-BSD.
////////////////////////
//MINIMAX FIR FILTERS///
////////////////////////
function demo_remezfilter()
// Low pass filter (length 33, cut-off in [.23,.27], weight 1/.1)
hn = eqfir(33,[0 .23;.27 .5],[1 0],[1 .1]);
[hm, fr] = frmag(hn, 256);
my_handle = scf(100001);
if is_handle_valid(my_handle) then
clf(my_handle, "reset");
plot2d(fr', hm')
title_c = [_("Minimax FIR filter");
_("low pass cut-off in [.23,.27]");
_("length 33")];
ax = gca();
ax.margins(3) = 0.2;
title(title_c);
halt(_("Press Return to continue ... \n"));
end
//Triangular filter created using remezb
nc = 21;
ngrid = nc * 16;
fg = .5*(0:(ngrid-1))/(ngrid-1);
ds(1:ngrid/2) = (0:-1+ngrid/2)*2/(ngrid-2);
ds(ngrid/2+1:ngrid) = ds(ngrid/2:-1:1);
wt = ones(fg);
[an] = remezb(nc, fg, ds, wt);
hn(1:nc-1) = an(nc:-1:2)/2;
hn(nc) = an(1);
hn(nc+1:2*nc-1) = an(2:nc)/2;
[hm, fr] = frmag(hn, max(size(ds)));
if is_handle_valid(my_handle) then
clf(my_handle, "reset");
plot2d(fr', hm'),
xtitle(_("Remez Triangular filter"), _("frequency"), ("magnitude"));
halt(_("Press Return to continue ... \n"));
end
if is_handle_valid(my_handle) then
clf(my_handle, "reset");
demo_viewCode("remezfilt.dem.sce");
plot2d(fr',( hm-ds)')
xtitle(" ", _("frequency"), _("magnitude error"));
end
endfunction
demo_remezfilter();
clear demo_remezfilter;
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