# Issues with Greek letters, bolding, and font packages

I am trying to write an exam for multivariable calculus, with \usepackage{bookman,eulervm} and I am running into some very, very stange errors:

1. When I try to use \mathbf{} on a Greek letter (e.g. \omega), LaTeX complies the symbol as something completely different: \mathbf{\omega} ends up making a boldface exclamation point; \mathbf{\tau} appears as a boldface nullset; \mathbf{\pi} appears as a boldface Eszett; etc. When I remove the font usepackage, the Greek letters simply fail to bold, but remain unchanged.

2. Inside one particular \begin{align*} (nested inside a \begin{enumerate} environment) I have the line:

&= (100\rm{rad}/\rm{sec})(20\rm{cm})(\sin(\pi/2))\\

and for the life of me, I cannot figure out why the \pi is rendering as the german letter ß!

It is acting like it does when I try to make the \pi boldfaced (with the bookman and eulervm packages), yet is not bold?!

Has anyone ever encountered this error before?

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I believe the unexpected ess-zett shows up because \rm is not a command that takes an argument but, instead, a switch: all subsequent material (until either some other font-changing command is encountered or until the current (math) environment ends) is instructed to show up in "roman" mode. It just so happens that the text-mode glyph that's in the same spot of the respective font table where \pi would be in the math mode font table happens to be the ess-zett.

Rather than using \rm -- which is a holdover from (Plain) TeX and is only barely supported by LaTeX -- you really should use either the \text macro of the amsmath package (which you're already loading anyway, it would appear) and/or create a few dedicated macros, such as

\newcommand\rad{\text{rad}}  % \text is a macro provided by the amsmath package
\newcommand\second{\text{sec}}
\newcommand\cm{\text{cm}}


and then write

\begin{align*}
\end{align*}


which will give you the output you'd expect to get. (Aside: You should probably write "s" rather than "sec" for second...)

\usepackage[mode=text,per-mode=symbol]{siunitx}


(as well as, of course, the amsmath, eulervm, and bookman packages). Then you could write the expression in question as

\begin{align*}

Finally, you mention encountering some problems with \mathbf; that works for (Latin) letters but not for other symbols (including various Greek letters). Use \boldsymbol for the latter symbols.