% -*- texinfo -*- % @deftypefn{Function File} {m = } ifht ( d, n, dim ) % @cindex linear algebra % The function ifht calculates Fast Hartley Transform % where @var{d} is the real input vector (matrix), and @var{m} % is the real-transform vector. For matrices the hartley transform % is calculated along the columns by default. The options @var{n}, % and @var{dim} are similar to the options of FFT function. % % The forward and inverse hartley transforms are the same (except for a % scale factor of 1/N for the inverse hartley transform), but % implemented using different functions . % % The definition of the forward hartley transform for vector d, % @math{ % m[K] = 1/N \sum_{i=0}^{N-1} d[i]*(cos[K*2*pi*i/N] + sin[K*2*pi*i/N]), for 0 <= K < N. % m[K] = 1/N \sum_{i=0}^{N-1} d[i]*CAS[K*i], for 0 <= K < N. } % % @example % ifht(1:4) % @end example % @seealso{fht,fft} % @end deftypefn