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如题:FRFT程序运行时说Not enough input arguments. 是怎么回事???7 ?- m! y5 S1 [7 `( e( ^& B4 E8 Y. j
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function Faf = frft(f, a)
/ Y' {. ?. v& J1 ^3 K1 ^3 R& V% The fast Fractional Fourier Transform% h4 L' u2 F* t, D* N
% input: f = samples of the signal2 G' v2 I6 ^' y! ^
% a = fractional power
" E& ?% [& j/ }8 s% output: Faf = fast Fractional Fourier transform error(nargchk(2, 2, nargin)); f = f( ;
7 R2 z* J# K s' a) R: R hN = length(f);
* R9 ]% x. }+ ^- @; bshft = rem((0:N-1)+fix(N/2),N)+1;5 r0 i; z( x7 e4 }6 G/ W8 f
sN = sqrt(N);/ y+ ]6 V+ B3 @5 z6 Y0 ^
a = mod(a,4); % do special cases
& Y: X/ L0 f& }if (a==0), Faf = f; return; end;
: d9 J0 [% R* O' y* Y& p/ t, Bif (a==2), Faf = flipud(f); return; end; |3 F: Q$ n! K# u# [! Z% x7 j
if (a==1), Faf(shft,1) = fft(f(shft))/sN; return; end - Q) `+ d4 c; e, F, U6 C+ j
if (a==3), Faf(shft,1) = ifft(f(shft))*sN; return; end % reduce to interval 0.5 < a < 1.5
. _; V9 k1 K8 G1 Z5 P" u* {if (a>2.0), a = a-2; f = flipud(f); end
4 x! z/ l1 i8 i, x! L+ Z L! p& J+ Sif (a>1.5), a = a-1; f(shft,1) = fft(f(shft))/sN; end3 j4 S& Q& S; g" c* E* Y+ a# |% m
if (a<0.5), a = a+1; f(shft,1) = ifft(f(shft))*sN; end % the general case for 0.5 < a < 1.52 `$ k% Z7 h; P/ A0 K) ^* n! l2 u
alpha = a*pi/2;" i {2 K8 u) ^3 m8 M3 g" g" z. V# `
tana2 = tan(alpha/2);4 \2 R* F/ T2 M9 o, Q# @; A+ n
sina = sin(alpha);
' L* z' H; ~( |$ w3 A$ Kf = [zeros(N-1,1) ; interp(f) ; zeros(N-1,1)]; % chirp premultiplication
4 p; z8 ?2 g+ u5 O0 D0 r# U0 Kchrp = exp(-i*pi/N*tana2/4*(-2*N+2:2*N-2)'.^2);" y: a% E: Y) v% i
f = chrp.*f; % chirp convolution0 }9 z% w ` w( \8 z+ ]
c = pi/N/sina/4;8 W4 H% v8 ]1 r
Faf = fconv(exp(i*c*(-(4*N-4):4*N-4)'.^2),f);2 u9 ?+ A8 n. E O; ]- p
Faf = Faf(4*N-3:8*N-7)*sqrt(c/pi); % chirp post multiplication0 g2 \! A) a5 ?, C
Faf = chrp.*Faf; % normalizing constant
0 w4 F3 e8 _! ]% {$ w- _Faf = exp(-i*(1-a)*pi/4)*Faf(N:2:end-N+1); %%%%%%%%%%%%%%%%%%%%%%%%%
- y0 N+ Q& [" W% Z( n. m, D0 ~5 [function xint=interp(x)
$ Q* C, d3 h; r- v" f7 F+ \% sinc interpolation N = length(x);
: o$ N: y9 F1 S- O& `; yy = zeros(2*N-1,1);
9 B$ g8 c6 F# ]& b" \, Q' Z8 ny(1:2:2*N-1) = x;
- r g! n: ^0 g6 }% Y+ j. Zxint = fconv(y(1:2*N-1), sinc([-(2*N-3) 2*N-3)]'/2));
- }) p9 ^9 I' `% }xint = xint(2*N-2:end-2*N+3); %%%%%%%%%%%%%%%%%%%%%%%%%
5 G0 }0 m- v" y$ H6 {" r8 A @( S# W3 Afunction z = fconv(x,y)) Z8 {; o% i, ]; g0 x. @$ A% K
% convolution by fft N = length([x( ;y( ])-1;9 u0 J' S* a% v& ~, s
P = 2^nextpow2(N);9 z& B* }# N% t# B' }+ d" F7 q! Y
z = ifft( fft(x,P) .* fft(y,P));
$ \7 @1 i5 T. U; n# cz = z(1:N); & h& }) W* t( Z
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