Best Approximation with Linear Constraints: A Model Example Original Research Article

We consider best approximation in Lp(R), 1 ≤ p ≤ ∞, by means of entire functions y of exponential type subject to additional constraints Γj(y) = 0, j = 1, ..., K. Here Γj are (unbounded) linear functionals of the form Γj(y) = Dny(sj) − ∑ akDky(sj) where sj are fixed points.