Numerical methods of approximation theory = Numerische methoden der approximationstheorie : Workshop on Numerical Methods of Approximation Theory, Oberwolfach, September 28-October 4, 1986 = Tagung uber Numerische Methoden der Approximationstheorie ... - Numerical Methods of Approximation Theory Workshop (1986 : Oberwolfach) (International series of numerical mathematics (ISNM) ; 81, 1987)