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//.............................................................................................................
// ................................Using "callOctave" method..............................
//.............................................................................................................
//function already exists in scilab -- doesnt work like this one (I guess)
//function y = interp(x, q, n, Wc)
//This function upsamples the signal x by a factor of q, using an order 2*q*n+1 FIR filter.
//Calling Sequence
//y = interp(x, q)
//y = interp(x, q, n)
//y = interp(x, q, n, Wc)
//Parameters
//x: scalar or vector of complex or real numbers
//q: positive integer value, or logical
//n: positive integer, default value 4
//Wc: non decreasing vector or scalar, starting from 0 uptill 1, default value 0.5
//Description
//This is an Octave function.
//This function upsamples the signal x by a factor of q, using an order 2*q*n+1 FIR filter.
//The second argument q must be an integer. The default values of the third and fourth arguments (n, Wc) are 4 and 0.5 respectively.
//Examples
//interp(1,2)
//ans =
// 0.4792743 0.3626016
//funcprot(0);
//rhs = argn(2)
//if(rhs<2 | rhs>4) source code says rhs<1 -- but crashes for just one arg
//error("Wrong number of input arguments.")
//end
//
//
//
//
// select(rhs)
// case 2 then
// y = callOctave("interp",x,q)
// case 3 then
// y = callOctave("interp",x,q,n)
// case 4 then
// y = callOctave("interp",x,q,n,Wc)
// end
//endfunction
//........................................................................................................
// .............................Using pure "Scilab"..........................................
//.........................................................................................................
//This function is built with the referrence of interp function (taken from interp.m file).
//Octave license:
// Copyright (C) 2000 Paul Kienzle <pkienzle@users.sf.net>
//
// 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 <http://www.gnu.org/licenses/>.
function y = oct_interp(x, q, varargin)
funcprot(0);
[nargout,nargin]=argn();
if nargin < 1 | nargin > 4,
error("Wrong Number of input arguments");
end
if q ~= fix(q), error("decimate only works with integer q."); end
if(nargin>2)
if(nargin==3)
n=varargin(1);
Wc=0.5;
else
n=varargin(1);
Wc=varargin(2);
end
else
n=4;Wc=0.5;
end
if size(x,1)>1
y = zeros(length(x)*q+q*n+1,1);
else
y = zeros(1,length(x)*q+q*n+1);
end
y(1:q:length(x)*q) = x;
b = fir1(2*q*n+1, Wc/q);
y=q*fftfilt(b, y);
y(1:q*n+1) = []; // adjust for zero filter delay
endfunction
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