xyInvFourier.m
79d454781fa3TekRSA-Freq-vs-Time

xyInvFourier.m
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			% the inverse function to xyFourier

			function [x_vect, y_vect] = xyInvFourier(freq_vect, sp_vect)
			assert(length(freq_vect)==length(sp_vect), ...
			'lengths of frequency and spectrum vectors should match')
			% We lease the check of the fact that the elements freq_vect are
			% equally spaced to the user for the sake of time saving

			% Make output column if the supplied frequency vector is column
			iscol=iscolumn(freq_vect);

			n=length(freq_vect);
			dx=1/(freq_vect(end)-freq_vect(1)); % step size in x domain
			x_vect=(1:n)*dx;

			if iscol
			x_vect=x_vect(:);
			end

			n_os=floor(n/2); % Maximum positive frequency index

			% Convert the spectrum vercot to column and reshape
			sp_vect=sp_vect(:);
			sp_vect=[sp_vect(end-n_os:end);sp_vect(1:end-n_os-1)];

			y_vect=sqrt(n/dx)*ifft(sp_vect);

			if ~iscol
			y_vect=transpose(y_vect);
			end
			end