A theorem on orthogonal functions with an application to integral inequalities
Lloyd L. Dines · Transactions of the American Mathematical Society · 1928
By a non-trivial solution we mean a solution which is not identically zero, t The case in which Df¿0 is compatible with the theorem, since in that case the equation ( 15) admits no non-trivial solution, and the inequality (12) admits a solution (14).