Possibly Germany, if you look at older STEM articles from mid 20. century they used Gothic Blackletter script for sine and the rest trigonometric funs. \Re and \Im are defined in article class and memoir, so they may well be old.
Aug 10, 2022, 00:28 by elro...@elronnd.net: > > I am curious where the convention of using black capital letters R and I to > indicate the real and imaginary parts of a complex number comes from. > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
