# Which font style is this?

Does anyone know which font style the 'a' circled in yellow in the image below is (this is in math mode)? My guess is euscript with mathcal, but it seems that mathcal does not apply to lowercase letters, unless I am wrong about that.

• mathcal is only upper case. – dustin Aug 14 '13 at 18:58
• this is euler cursive. the latex support is rudimentary, but the font is defined in the file ueur.fd (part of amsfonts), and it wouldn't be difficult to provide more functional support by adapting the definitions in euscript.sty (also part of amsfonts). – barbara beeton Aug 14 '13 at 19:55

\documentclass{article}
$\sum_m \EulerRM{a}_m u_m(y)$