Who introduced the term sinus cardinalis? I do not mean the abbreviation sinc, which was introduced 1952 by Woodward.


According to sources quoted in Wikipedia's sinc "talk" page,

The name sinus cardinalis dates back by Edmund T. Whittaker in 1915, where he named the bandlimited or most simple function of a family of cotabular functions (sharing a function table, i.e., values at equally spaced sample points) the cardinal function of this family. One would have to check if he already named the basis functions or if that came later. See A History of interpolation.--LutzL (talk)

Following that "talk" link leads to a history page which includes an image from that paper, From E. T. Whittaker, "On the Functions which are Represented by the Expansions of Interpolation-Theory", Proceedings of the Royal Society of Edinburgh, vol. 35, 1915, pp. 181-194

whittaker excerpt

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    $\begingroup$ The Wikipedia page doesn’t say that, nor do the words “cardinal” or “cardinalis” appear in the quoted 1952 paper and 1953 book. $\endgroup$ – Francois Ziegler Jun 25 '18 at 14:44
  • $\begingroup$ @FrancoisZiegler I stand corrected -- the text of the WIki page was rather misleading. I'll try to update my answer shortly $\endgroup$ – Carl Witthoft Jun 25 '18 at 15:29
  • $\begingroup$ I think you’re right that the name “cardinal” for interpolation series goes back to Whittaker. But who first called the sinc function “cardinal sine” remains anyone’s guess. Whittaker (1915) certainly doesn’t, nor does Woodward imply that “c” is for cardinal. $\endgroup$ – Francois Ziegler Jun 25 '18 at 19:11

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