The Long Shadow of Karl Weierstraß Over the Calculus of Variations

At first glance, it appears that the contents of Karl Weierstraß's (1815–1897) lecture courses on the calculus of variations were made available to the public only in the seventh volume of his Mathematische Werke , and thus not until 30 years after his death. In reality, however, this material had already found its way into textbooks of other mathematicians, who duly acknowledged Weierstraß's contributions; notable examples include Adolf Kneser (1862–1930) with his Lehrbuch der Variationsrechnung of 1900 and Oskar Bolza (1857–1942) with his Lectures on the Calculus of Variations of 1904 and its translation, Vorlesungen über Variationsrechnung of 1909. Of particular importance for the dissemination of Weierstraß's contributions to the calculus of variations was the lecture course he delivered during the summer semester of 1879, which served as the basis of a worked‐out set of lecture notes published by the “Mathematischer Verein” at the University of Berlin. Furthermore, Weierstraß discussed the calculus of variations in his letters to Hermann Amandus Schwarz (1843–1921), particularly regarding his plans for a textbook on this subject.