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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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# H- [! ~% P- p2 s+ Vfunction Faf = frft(f, a)
6 T, y8 R* _) ^. A) a5 R& H, B! R% The fast Fractional Fourier Transform6 I) G9 `) d6 [3 S( s
% input: f = samples of the signal
& g$ K; B, `0 N3 ^% z# ? K% a = fractional power) ^" ~- q, M4 K' F- p# ?
% output: Faf = fast Fractional Fourier transform error(nargchk(2, 2, nargin)); f = f( ;
1 @* p, d! A& c2 O. p/ A8 WN = length(f);
8 K$ y7 i) r1 Z% A% Ashft = rem((0:N-1)+fix(N/2),N)+1;# Z) Y. o: m4 q O6 \
sN = sqrt(N);
! H9 n4 i) u7 B. z# M+ O3 W da = mod(a,4); % do special cases+ d7 f& ~: k5 s- v( c
if (a==0), Faf = f; return; end;! w7 y. q6 d* a& B* Y8 f- b
if (a==2), Faf = flipud(f); return; end;5 b9 h/ L; ?) L' X5 D2 K4 v
if (a==1), Faf(shft,1) = fft(f(shft))/sN; return; end
: `8 F: h5 ~7 W0 i. k% Qif (a==3), Faf(shft,1) = ifft(f(shft))*sN; return; end % reduce to interval 0.5 < a < 1.5
+ P |5 i" \$ y: v' N' @if (a>2.0), a = a-2; f = flipud(f); end) Q1 _; C) r3 N' t
if (a>1.5), a = a-1; f(shft,1) = fft(f(shft))/sN; end* f, O9 J% @9 e
if (a<0.5), a = a+1; f(shft,1) = ifft(f(shft))*sN; end % the general case for 0.5 < a < 1.5# s' j- T5 w' u; ]/ w
alpha = a*pi/2;
- D2 G X, f% V, F8 `) ftana2 = tan(alpha/2);- Q9 e2 P7 v" `( J8 }6 _5 Y! w8 K+ b
sina = sin(alpha);
% ~- N# f8 E+ uf = [zeros(N-1,1) ; interp(f) ; zeros(N-1,1)]; % chirp premultiplication
/ L; G3 z, c7 O4 [1 v( P6 W Qchrp = exp(-i*pi/N*tana2/4*(-2*N+2:2*N-2)'.^2);6 c" R1 v4 |$ _
f = chrp.*f; % chirp convolution
% a d3 c2 |! R6 g0 [c = pi/N/sina/4;2 |% v, F9 C4 ]" Z1 |$ c+ D
Faf = fconv(exp(i*c*(-(4*N-4):4*N-4)'.^2),f);$ a7 x1 j3 C e8 b+ F+ J# p; ]+ p
Faf = Faf(4*N-3:8*N-7)*sqrt(c/pi); % chirp post multiplication
: n; U3 v- v3 {1 |$ ~Faf = chrp.*Faf; % normalizing constant. E" E3 C" V& h5 s
Faf = exp(-i*(1-a)*pi/4)*Faf(N:2:end-N+1); %%%%%%%%%%%%%%%%%%%%%%%%%
: C7 E; N+ ^- I0 h1 vfunction xint=interp(x)
- J8 J7 l' [. A0 D% sinc interpolation N = length(x);
3 ~: D) {) c' N& L3 G& H+ H0 i1 R `y = zeros(2*N-1,1);
2 A2 T+ E- p5 f. r Q2 s& xy(1:2:2*N-1) = x;$ I4 _1 [" T7 @" }
xint = fconv(y(1:2*N-1), sinc([-(2*N-3) 2*N-3)]'/2));
; y, X2 m I! ?* K' @- l4 [( J; ]xint = xint(2*N-2:end-2*N+3); %%%%%%%%%%%%%%%%%%%%%%%%%
9 {* B, h7 T* [/ I/ {function z = fconv(x,y). e1 M; D4 O7 a$ o) K
% convolution by fft N = length([x( ;y( ])-1;6 S0 Y; z$ P& j2 S# z0 N
P = 2^nextpow2(N);" O2 ^1 V7 R4 u* Z- ~8 {8 f5 f
z = ifft( fft(x,P) .* fft(y,P));
, E* N3 Q: M# e, Az = z(1:N);
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