I would like to typeset the differential of a multivariate function evaluated at a point where two of the variables take precise value. I typeset the "evaluated at" using a vertical bar, at the bottom of which I indicate the point at which it's evaluated.
When it's evaluated at just "one variable", no problem, I would just do:
$\left.
\frac{\partial f}{\partial x}
\right|_{y=0}$
But how could I evaluate the derivative at y=0, z=1
? I could write it in one line but it becomes quite long. So ideally I would like to "stack" them. At the moment, I use:
$\left.
\frac{\partial f}{\partial x}
\right|_{\mathop{z=1}\limits^{y=0}}$
which is very kludgy to say the least. And it doesn't work very nicely: the y=0
is typeset a bit smaller than the z=0
.
Any idea on how I could do this properly?
\substack
command:$\left.\frac{\partial f}{\partial x}
\right|_{\tiny\substack{y=0\\ z=1}}$
The\tiny
is optional, and actually throws in a warning that it's not valid in math mode, so it's probably not the exact perfect solution. Also the second line is further down than the vertical bar, but that's a start.\substack
command is actually provided by the amsmath package (in its v2.0 at least).