# 每日一言 - 5月31日言

The theory of Fourier series and integrals has always had major difficulties and necessitated a large mathematical apparatus in dealing with questions of convergence. It engendered the development of methods of summation, although these did not lead to a completely satisfactory solution of the problem…. For the Fourier transform, the introduction of distributions (hence the space $\mathscr{S}$) is inevitable either in an explicit or hidden form…. As a result one may obtain all that is desired from the point of view of the continuity and inversion of the Fourier transform.

*L. Schwartz*, 1950

# Daily Words - 每日一言 - 5月21日言

Quoted by Mittag-Leffler: Compute rendudu deuxième congrês international des mathémaé-ciens(Paris, 1902)