📄 disfrst.mht
字号:
From: <óé Microsoft Internet Explorer 5 ±￡′?>
Subject:
Date: Fri, 10 Sep 2004 12:04:36 +0800
MIME-Version: 1.0
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Location: http://www.cs.kuleuven.ac.be/cwis/research/nalag/research/software/FRFT/Disfrst.m
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.2180" name=GENERATOR></HEAD>
<BODY><PRE>function y = Disfrst(f,a,p)
% Computes discrete fractional sine transform
% of order a of vector f
% p (optional) is order of approximation, default N/2
% S-C Pei, M-H Yeh, IEEE Tr SP 49(6)2001, pp.1198-1207
N = length(f);
shft = rem((0:N-1)+fix(N/2),N)+1;
f = f(:);
if (nargin==2), p = N/2; end;
p = min(max(2,p),N-1);
E = dFRST(N,p);
y=E*(exp(-j*pi*a*([0:N-1])).'.*(E'*f));
function E=dFRST(N,p)
%function E=dFRST(N,p) returns the NxN eigenvectors of the
%Fourier Sine transform matrix
global ES_saved pS_saved
if (length(ES_saved) ~= N | pS_saved ~= p),
E = make_ES(N,p);
ES_saved = E; pS_saved = p;
else
E = ES_saved;
end;
function E = make_ES(N,p)
% Returns sorted eigenvectors and eigenvalues of corresponding vectors
% Construct matrix H, use approx order p
N1=2*N+2;
d2 = [1 -2 1]; d_p = 1; s = 0; st = zeros(1,N1);
for k = 1:p/2,
d_p = conv(d2,d_p);
st([N1-k+1:N1,1:k+1]) = d_p; st(1) = 0;
temp = [1:k;1:k]; temp = temp(:)'./[1:2*k];
s = s + (-1)^(k-1)*prod(temp)*2*st;
end;
H = toeplitz(s(:),s)+diag(real(fft(s)));
% Construct transformation matrix V
r = N;
V = [zeros(N,1),flipud(eye(N)),zeros(N,1),-eye(N)]/sqrt(2);
% Compute eigenvectors
Od = V*H*V';
[vo,eo]=eig(Od);
% malab eig returns sorted eigenvalues
% if different routine gives unsorted eigvals, then sort first
% [d,inde] = sort(diag(eo));
% vo = vo(:,inde');
E = flipud(fliplr(vo));
</PRE></BODY></HTML>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -