Prevent spacing in sub or super scripts with eulervm

Question

When typing formulas to explain physics, sometimes non spaced text in super or subscripts is helpful.

$q_{heat}$

To prevent spacing in subscripts, I often used \textit in math mode:

$q_{\textit{heat}}$

since I use classic thesis together with eulervm, the \textit trick doesn't work any more, because text font changes.

Is there a better way to prevent spacing without changing the font?

How do I define a \texteulervm environment correctly?

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As an example what happens, the following code:

j_{WDR,runoff}^{w} & \ne j_{\text{WDR,runoff}}^{w}

results in:

please note the difference in the subscript.

Answer 1

Not a solution according to your wishes, but it is according to well established standards.

The purpose of using Euler for math is to get a sharp visual distinction between text and math: letters for variables and digits are very different from any text font.

On the other hand, ‘WDR’ and ‘runoff’ are not math variables, but specifiers for distinguishing between variables with the same name. Just like they should be typeset upright when not using Euler, they should be upright and in the text font also with it. It's a similar situation as with function names such as ‘log’ or ‘sin’ that should be typeset in the text font and not in Euler.

A hypothetical $j_{WDR}$ means j subscripted with the product of W, D and R, while $j_{\textnormal{WDR}} means what you really intend: the variable j subscripted with the label WDR.

Also your habit of typing $j_{\textit{heat}}$ is wrong, according to the standards: it should be $j_{\textnormal{heat}}$, at least if ‘heat’ is a label and not a variable taking a value.

Answer 2

define a command \texteuler:

\def\texteuler#1{{\fontencoding{U}\fontfamily{zeur}\selectfont\text{#1}}}