Gentleman detective shares some features with the later gentleman detective. He was "…the first fictional detective of importance and the model for virtually every cerebral crime solver who followed." More specifically, Dorothy L. Sayers noted that "Sherlock Holmes modelled himself to a large extent upon (Poe's) Dupin, substituting cocaine for candlelight, with accompaniments of shag and fiddle-playing." Dupin is French, not English, but is probably a "gentleman". He comes from a once wealthy family but has been reduced "by a variety of untoward events" to more humble circumstances. He is entirely amateur and contents himself only with the basic necessities of life.
Dupin cyclide "R" are a 3-dimensional vectors, and "A" and "B" are constants. Families of cyclides give rise to various cyclidic coordinate geometries. In Maxime Bôcher's 1891 dissertation, "Ueber die Reihenentwickelungen der Potentialtheorie", it was shown that the Laplace equation in three variables can be solved using separation of variables in 17 conformally distinct quadric and cyclidic coordinate geometries. Many other cyclidic geometries can be obtained by studying R-separation of variables for the Laplace equation. Dupin cyclide In mathematics, a Dupin cyclide or cyclide of Dupin is any geometric inversion of a standard torus, cylinder or double cone. In particular, these latter