181. http://hea-www.harvard.edu/AstroStat/astro193/scientificamerican0689-86.pdf
... Whereas the Fourier transform involves real and imaginary numbers and a complex sum of sinus oidal functions, the Hartley transform involves only real numbers and a real sum of sinusoidal functions. ... Hartley gave up the directIon of his SCIENTIFIC AMERICAN June 1989 ? 1989 SCIENTIFIC AMERICAN, INC 93 THE FOURIER AND HARTlEY TRANSFORMS The Fourier and Hartley transforms convert functions of time into functions of frequency that encode phase and amplitude information. ... THE HARTLEY TRANSFORM. ...