A detailed proof of Whitney's Theorem from 1957, giving an upper bound on the rate of approximation of the space L_p[a,b] from polynomials. The upper bound is given through the modulus of smoothness. Included is the special case of 0<p<1.
An introduction to the Radon tranform. We derive the classical fourier slice theorem, and give a complete proof showing the reconstruction of a function from its Radon tranform using orthogonal ridge polynomials.