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
|
function F = sgolay (p, n, m, ts)
//This function computes the filter coefficients for all Savitzsky-Golay smoothing filters.
//Calling Sequence
//F = sgolay (p, n)
//F = sgolay (p, n, m)
//F = sgolay (p, n, m, ts)
//Parameters
//p: polynomial
//n: odd integer value, larger than polynomial p
//m: positive integer less than 2^31 or logical
//ts: real or complex value
//Description
//This function computes the filter coefficients for all Savitzsky-Golay smoothing filters of order p for length n (odd).
//m can be used in order to get directly the mth derivative; ts is a scaling factor.
//Examples
//y = sgolay(1,3,0)
//y =
// 0.83333 0.33333 -0.16667
// 0.33333 0.33333 0.33333
// -0.16667 0.33333 0.83333
if(argn(2)<2 | argn(2)>4) then
error("Wrong number of input arguments.")
elseif ((n-fix(n./2).*2)~=1) then
error ("sgolay needs an odd filter length n");
elseif (p>=n) then
error ("sgolay needs filter length n larger than polynomial order p");
end
if (argn(2)==2) then
m=0; ts=1;
end
if (argn(2)==3) then
ts=1;
end
if length(m) > 1, error("weight vector unimplemented"); end
F = zeros (n, n);
k = floor (n/2);
for row = 1:k+1
C = ( [(1:n)-row]'*ones(1,p+1) ) .^ ( ones(n,1)*[0:p] );
A = pinv(C);
F(row,:) = A(1+m,:);
end
F(k+2:n,:) = (-1)^m*F(k:-1:1,n:-1:1);
F = F * ( prod(1:m) / (ts^m) );
endfunction
|
