Here's a simple demonstration program:

```
\documentclass[12pt]{article}
\usepackage[utf8x]{inputenc}
\DeclareMathVersion{sans}
\SetSymbolFont{letters}{sans}{OT1}{cmss}{m}{sl}
\begin{document}
\[
x + \alpha \beta
\]
\mathversion{sans}
\[
x + \alpha \beta
\]
\end{document}
```

It works fine, but the sans serif math does not have correct greek characters. Adding the following lines almost fixes the problem:

```
\usepackage[LGR]{fontenc}
\DeclareSymbolFont{grekletters}{LGR}{cmr}{m}{sl}
\DeclareMathSymbol{\alpha}{\mathord}{grekletters}{`a}
\DeclareMathSymbol{\beta}{\mathord}{grekletters}{`b}
%...
\SetSymbolFont{grekletters}{sans}{LGR}{cmss}{m}{n}
```

But now the Greek characters in math mode are not the original ones. Where are the original ones?

There's a similar question:

Replacing greek glyphs in math mode. It is about luatex, though.

Also, I cannot use the `sansmath`

package because it does not support my font encoding.

## Best Answer

The

`letters`

font should be a font encoded as`OML`

, not`OT1`

; you can use CMBright for those and for the`OMS`

family; a decent substitute for the large symbols can be Iwona: