This is from a scan of an old math book - pre-LaTeX.
I’ve tried all the usual suspects in latex (euscript, fraktur, mathcal) and they are a poor match, euscript comes closest.
I’ve also tried the various online Identifonts and had no luck either.
There probably wasn’t that much variety in tyepsetting math texts during the 1950s, so i’m hoping a wise and gentle greybeard (male/female) might know the answer.
If it helps, the body font (not shown) seems to be Times New Roman - no surprise there.
Glyphs shown: V C P F
(yes, that’s a cal “C” not an “e”. The context makes that clear)
Thanks for any help,