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如题:FRFT程序运行时说Not enough input arguments. 是怎么回事???2 s- Y N9 ~4 `3 w( @) n2 }4 c
. `- n% c w% g4 T0 p( ^function Faf = frft(f, a)" J( x' U* E- ]6 J
% The fast Fractional Fourier Transform
0 B0 j; Y2 k$ ^4 l, ^/ k% input: f = samples of the signal/ y. j' t- o6 g4 z1 @
% a = fractional power/ R7 S( r1 S0 D/ y
% output: Faf = fast Fractional Fourier transform error(nargchk(2, 2, nargin)); f = f( ;
& j% _7 \1 o; c I. r" J8 IN = length(f);
! m% m" J1 |8 gshft = rem((0:N-1)+fix(N/2),N)+1;; O2 O: g5 Q4 K8 Y+ _' U6 G
sN = sqrt(N);/ w7 T4 Q$ g3 B
a = mod(a,4); % do special cases9 i! U8 `3 W- U- @& q
if (a==0), Faf = f; return; end;. A: A9 Q& h% @7 Z
if (a==2), Faf = flipud(f); return; end;2 y; \% j1 {! v/ q/ v/ X
if (a==1), Faf(shft,1) = fft(f(shft))/sN; return; end 9 D% M0 z: W, H* ?1 h4 P* I0 S" k
if (a==3), Faf(shft,1) = ifft(f(shft))*sN; return; end % reduce to interval 0.5 < a < 1.52 h! r6 l2 X% ]! J" h
if (a>2.0), a = a-2; f = flipud(f); end* \' I9 D" P; a* Q X( P# S3 e! Y) c2 X
if (a>1.5), a = a-1; f(shft,1) = fft(f(shft))/sN; end7 U6 N# k: w0 ?% C/ g& m
if (a<0.5), a = a+1; f(shft,1) = ifft(f(shft))*sN; end % the general case for 0.5 < a < 1.5# r. R0 V' M- ]3 m; s" J5 _
alpha = a*pi/2;# X/ X6 F( K$ f/ T/ A+ D
tana2 = tan(alpha/2);0 k- K0 f, x; D/ I' [( A
sina = sin(alpha);
9 J2 k9 h% w5 J& Vf = [zeros(N-1,1) ; interp(f) ; zeros(N-1,1)]; % chirp premultiplication4 ]1 e& Z- O3 ^% H9 K: w
chrp = exp(-i*pi/N*tana2/4*(-2*N+2:2*N-2)'.^2);
1 m0 d/ F' }, W0 c" ^7 f) Pf = chrp.*f; % chirp convolution7 n( S) y% E+ G
c = pi/N/sina/4;, v) l1 j- n2 K' u3 a0 c1 @
Faf = fconv(exp(i*c*(-(4*N-4):4*N-4)'.^2),f);, ^9 s8 w$ P0 l8 B+ S- N
Faf = Faf(4*N-3:8*N-7)*sqrt(c/pi); % chirp post multiplication! O7 I& U, n. b3 G v" h/ I7 B9 n
Faf = chrp.*Faf; % normalizing constant; e9 `" Q1 `! D9 r" w/ Y: }
Faf = exp(-i*(1-a)*pi/4)*Faf(N:2:end-N+1); %%%%%%%%%%%%%%%%%%%%%%%%%! e }" o6 ^+ P. z8 B4 F
function xint=interp(x)6 U* q% C' ]+ p3 [; o( i
% sinc interpolation N = length(x);
6 N7 M% d7 h6 {, U8 wy = zeros(2*N-1,1);
7 [4 D; Z/ j; P% c4 H7 yy(1:2:2*N-1) = x;9 L/ F0 t, C8 t$ [- b, }4 d
xint = fconv(y(1:2*N-1), sinc([-(2*N-3) 2*N-3)]'/2));# u) \9 @# N2 A1 r; Y9 ?0 f( P
xint = xint(2*N-2:end-2*N+3); %%%%%%%%%%%%%%%%%%%%%%%%%& }! k/ q; ]! {9 _
function z = fconv(x,y), j6 w& `7 ^$ o. P
% convolution by fft N = length([x( ;y( ])-1;
& r) J; h0 b7 D# b3 H/ dP = 2^nextpow2(N);
* r- H1 ^/ _. @- N! dz = ifft( fft(x,P) .* fft(y,P));/ x$ Y# b+ ]$ q& k* `. {1 j0 x/ A
z = z(1:N);
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