function [d]=forward_radon(m,dt,h,p,N,flow,fhigh);%FOR_RADON: Forward linear and parabolic Radon transform. %  Given a Radon panel (tau-p), this function  maps %  the tau-p gather into time-offset space (data).%%  [d] = forward_taup(m,dt,h,p,N,flow,fhigh);%%  IN   m:     the Radon panel, a matrix m(nt,np)%       dt:    sampling in sec%       h(nh): offset or position of traces in mts%       p(np): ray parameter  to retrieve if N=1%              curvature of the parabola if N=2%       N:     N=1 linear tau-p%              N=2 parabolic tau-p%       flow:  min freq. in Hz%       fhig:  max freq. in Hz%%  OUT  d:     data%%%  Author(s): M.D.Sacchi (sacchi@phys.ualberta.ca)%  Copyright 1988-2003 SeismicLab%  Revision: 1.2  Date: Dec/2002 %  %  Signal Analysis and Imaging Group (SAIG)%  Department of Physics, UofA%[nt,nq] = size(m);     nh = length(h); if N==2; h=(h/max(abs(h))).^2; end;    nfft = 2*(2^nextpow2(nt)); M = fft(m,nfft,1); D = zeros(nfft,nh); i = sqrt(-1); ilow  = floor(flow*dt*nfft)+1;  if ilow < 1; ilow=1; end; ihigh = floor(fhigh*dt*nfft)+1; if ihigh > floor(nfft/2)+1; ihigh = floor(nfft/2)+1; end  for ifreq=ilow:ihigh  f = 2.*pi*(ifreq-1)/nfft/dt;  L = exp(i*f*h'*p);  x = M(ifreq,:)';  y = L * x;   D(ifreq,:) = y';  D(nfft+2-ifreq,:) = conj(y)'; end D(nfft/2+1,:) = zeros(1,nh); d = real(ifft(D,[],1)); d = d(1:nt,:);return;