The founder of the Institute, Tiberiu Popoviciu, has obtained some outstanding results:

  • introduction of the B-spline functions on nonuniform grids, in 1934, (as acknowledged in a paper by C. de Boor and A. Pinkus, and in a subsequent paper of C. de Boor), studied in depth, obtaining the (now called) Marsden recurrence identity from 1970, and the (now called) Boehm’s knot insertion formula, from 1980;
  • introduction of the cardinal spline interpolation on arbitrary knots, in 1941, as acknowledged by I.J. Schoenberg himself, in a paper published in Mathematica, in 1968: “In [1941] Popoviciu uses spline functions directly for the purpose for which they are so eminently suited: the approximation of functions. He introduces spline functions of degree n with arbitrary knots…”
  • first use of the modulus of continuity for obtaining estimations for the remainders in approximation formulas, in 1937;
  • prefiguration of the de Casteljau algorithm, by considering the alternative computation of the value of the Bernstein polynomial, in 1937;
  • generalization of the Leibniz formula for the product of two functions to divided differences, in 1933;
  • introduction and study of the convex functions of higher order, in 1933 and 1945;

Tiberiu Popoviciu appears in the select History of Approximation Theory (Technion University, Israel).