Added codegen folder and scripts for fracF operating in DPW (matrix)

codegen_fracFdpw/fracF_init.m

@@ -0,0 +1,70 @@
+function [Achirp,AchirpOut,H,scale] = fracF_init(a)
+%#codegen
+%
+% fracF_init
+%
+% Precompute FrFT coefficients for DPW processing.
+%
+% INPUT:
+%   a  - FrFT order (single)
+%
+% OUTPUTS:
+%   Achirp     [1024 x 1]
+%   AchirpOut  [512  x 1]
+%   H          [2048 x 1]
+%   scale      scalar
+
+N    = 1024;
+
+pi_s = single(pi);
+
+phi = a * (pi_s/2);
+
+tan_half_phi = tan(phi/2);
+sin_phi      = sin(phi);
+cos_phi      = cos(phi);
+
+csc_phi = 1/sin_phi;
+cot_phi = cos_phi/sin_phi;
+
+twoDelta = 2*sqrt(single(N)/2);
+
+%% Chirp A
+
+n = single((-N/2:N/2-1).') / twoDelta;
+
+Achirp = exp(-1j*pi_s*(n.^2)*tan_half_phi);
+
+%% Chirp B
+
+m = single((-N:N-1).') / twoDelta;
+
+Bchirp = exp(1j*pi_s*csc_phi*(m.^2));
+
+%% FFT of Chirp B
+
+H = fft(Bchirp);
+
+%% Output chirp
+
+AchirpOut = Achirp(1:2:end);
+
+%% Scale factor
+
+scale = sqrt(1 - 1j*cot_phi) / twoDelta;
+
+%% Force single precision complex
+
+Achirp    = complex(single(real(Achirp)), ...
+                    single(imag(Achirp)));
+
+AchirpOut = complex(single(real(AchirpOut)), ...
+                    single(imag(AchirpOut)));
+
+H         = complex(single(real(H)), ...
+                    single(imag(H)));
+
+scale     = complex(single(real(scale)), ...
+                    single(imag(scale)));
+
+end