# Unknown math font

I am trying to identify the font used for the integral sign and letter x here:

Any ideas?

• My guess is that is not an x, but more likely a \kappa, similar to commons.wikimedia.org/wiki/… – Steven B. Segletes Dec 1 '20 at 15:31
• do you have the pdf for that formula? (if so you can list the fonts exactly) – David Carlisle Dec 1 '20 at 15:44
• @DavidCarlisle No. Just that picture. – Robert W. Dec 1 '20 at 15:45
• Note that the kappa symbol is slanted after d, but it is unslanted after sin, cos. It seems that your picture is a result of typesetting work of an amateur. The integral symbol is from bold variant of a math font but the rest isn't. – wipet Dec 1 '20 at 15:46
• @RobertW. My tip is that this is not TeX (i.e. no LaTeX, no latex package). There are slanted/unslanted version of kappa, the spaces between sin, cos and their arguments are missing, there is a mix of bond/nobold symbols. Of course, I am able to do such obscure things by TeX, but it is more complicated task:). – wipet Dec 1 '20 at 15:57

I think this is the symbol \varkappa (you need the package amssymb).