Yes, \underset. My old macro (see sister comment) ensures math mode, switches to a smaller font, uses a "x" (\times). You'd then write (with \cdots for better s

Yes, \underset. My old macro (see sister comment) ensures math mode, switches to a smaller font, uses a "x" (\times). You'd then write (with \cdots for better spacing) \ddim Umr \cdot \ddim {\Sigma}rr = \ddim Amn \cdot \ddim Vnr to get https://www.fabian-lischka.de/files/Various/ddim-ex3.png https://www.fabian-lischka.de/files/Various/ddim-ex3.png