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如题:FRFT程序运行时说Not enough input arguments. 是怎么回事???
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function Faf = frft(f, a)/ M# u; k; @4 V* e& Z9 @6 O
% The fast Fractional Fourier Transform. i1 J+ P7 K1 Z) Y! M' {4 {8 w8 i
% input: f = samples of the signal! c6 V: x) U* s% m" z1 e% F F/ Y
% a = fractional power
. B% L5 x4 U2 M2 s% output: Faf = fast Fractional Fourier transform error(nargchk(2, 2, nargin)); f = f( ;
; F0 W) [! G6 i aN = length(f);0 w$ o6 Y3 Q5 E! Q' e3 n9 \
shft = rem((0:N-1)+fix(N/2),N)+1;0 N/ f+ A! t( L! R8 D- [$ N9 I
sN = sqrt(N);, d) i4 d- V( P
a = mod(a,4); % do special cases
5 O1 i3 p0 i/ e# ]9 K: m0 a7 |if (a==0), Faf = f; return; end;/ _8 O+ | m. Y! x' i8 p, H- z9 W
if (a==2), Faf = flipud(f); return; end;
_1 O! m; D! H; Gif (a==1), Faf(shft,1) = fft(f(shft))/sN; return; end $ a4 ?. R) e2 O6 k( ~) e9 a3 P
if (a==3), Faf(shft,1) = ifft(f(shft))*sN; return; end % reduce to interval 0.5 < a < 1.5
% W, u$ }, A3 t1 {$ b6 w B8 Hif (a>2.0), a = a-2; f = flipud(f); end' I$ `; h' }! |% I1 g9 L& M9 ?
if (a>1.5), a = a-1; f(shft,1) = fft(f(shft))/sN; end
8 |9 M$ Z, l& ?& q: V" y) Tif (a<0.5), a = a+1; f(shft,1) = ifft(f(shft))*sN; end % the general case for 0.5 < a < 1.5* i3 |$ \3 x i5 w6 J4 F" f: z
alpha = a*pi/2;. f1 ] {: ^5 O0 o- L% ~( i y
tana2 = tan(alpha/2);, V% F; i9 F% ~
sina = sin(alpha);
2 I, I- B+ L( y9 T/ g: K! Nf = [zeros(N-1,1) ; interp(f) ; zeros(N-1,1)]; % chirp premultiplication6 U2 B/ T* J& Z1 h% p- n, d
chrp = exp(-i*pi/N*tana2/4*(-2*N+2:2*N-2)'.^2);; I6 X, h' Z7 ^9 V" h7 D, k2 O3 |8 R
f = chrp.*f; % chirp convolution
8 _ ^$ j; I4 uc = pi/N/sina/4;- b. L2 B" J( X
Faf = fconv(exp(i*c*(-(4*N-4):4*N-4)'.^2),f);
$ @, ?4 h' h8 N6 e; d5 p5 VFaf = Faf(4*N-3:8*N-7)*sqrt(c/pi); % chirp post multiplication2 D# [+ Q% y) ^+ d7 d% y
Faf = chrp.*Faf; % normalizing constant
8 U/ h3 V; M+ O! u2 K& BFaf = exp(-i*(1-a)*pi/4)*Faf(N:2:end-N+1); %%%%%%%%%%%%%%%%%%%%%%%%%
( t, p2 h5 v' `3 k7 {" Sfunction xint=interp(x)# N B0 y6 B+ H1 o! z; B6 i0 ~# j
% sinc interpolation N = length(x);
* q& Y: b+ Q, ~, }1 n1 {" Z% H8 qy = zeros(2*N-1,1);
% U: |- [0 ~4 s& J6 G$ {; ~+ Iy(1:2:2*N-1) = x;; z) \: O% G& b
xint = fconv(y(1:2*N-1), sinc([-(2*N-3) 2*N-3)]'/2));
# Q( ~" T9 o- O4 B8 oxint = xint(2*N-2:end-2*N+3); %%%%%%%%%%%%%%%%%%%%%%%%%4 q5 P; i: Q; U/ M: l9 |
function z = fconv(x,y)
7 }1 K& f Z! U* B% |% convolution by fft N = length([x( ;y( ])-1;
! K% w/ d% @! x: A J1 bP = 2^nextpow2(N);
6 E& w# y' q5 {) f2 y Cz = ifft( fft(x,P) .* fft(y,P));
6 z' E3 j) L: _! q& e4 U1 kz = z(1:N); ) n6 ~7 X; B) B* {1 h7 ?, ]- s6 ?
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