Half point font sizes in AMS book [duplicate]

How can I typeset my book in a 10.5pt font size using the `amsbook` document class? I tried using

``````\fontsize{10.5}{12}\selectfont
``````

but it doesn't seem to work.

• Since `amsbook` uses Computer Modern, you can just `\usepackage{fix-cm}` in the preamble. Alternatively, `\usepackage{lmodern}`. – Werner Apr 25 '16 at 17:46
• if you want to change font sizes with `amsbook`, it's probably best to copy that file to another name. then look for the definition of the command `\@typesizes`. examine the definitions for the various font sizes (they are mostly named with roman numerals), and when you understand their relation to one another, you can change the sizes associated with each consistently. the definitions are reasonably clear, and they are used consistently, so this should be doable if you already know enough to ask about `\fontsize`. – barbara beeton Apr 25 '16 at 17:53