Commentary on: , , and 
In his search for surfaces all of whose geodesies are closed and have the same length, Funk proved (1916) that an even function on the sphere S 2 is determined by its integral over the great circles. Shortly afterwards (1917), Radon showed that a function f on R n is determined by its hyperplane integrals. The transformation f → f which to f associates its hyperplane integrals circumplexf(ξ) = ∫ξ f(x) dm(x) is now called the Radon transformation.
Unable to display preview. Download preview PDF.