[Tex/LaTex] Spacing lines in mathmode

math-modespacing

I need to explain two different elements in two different lines of an equation in math mode. I'm using this piece of code:

\begin{align*}
h(z)=0 &\Leftrightarrow \sinh\frac{1}{z}=0 \markno{\Leftrightarrow}{According to ...} \frac{2}{z} = 2\pi i n  \\&\marknoup{\Leftrightarrow}{$n$ is whole} z = \frac{i}{\pi n}
\end{align*}

(I'm shortening to make it clearer)

I'm using these macros:

\newcommand\markno[2]{\begin{array}[t]{@{\,}c@{\,}} #1 \\ \downarrow \\ \makebox[0pt]{\scriptsize #2} \end{array}}
\newcommand\marknoup[2]{\begin{array}[b]{@{\,}c@{\,}} \makebox[0pt]{\scriptsize #2}\\ \uparrow \\ #1 \end{array}}

The thing is, that LaTeX automatically spaces the lines, so that the "According two" is above (in height) "n is whole". I'm using two different arrows exactly to avoid that; I want them to overlap in height, in order to save space.

I tried using \vspace, but for some reason it doesn't work well for me.

Best Answer

You can manually adjust the space between the lines in an align environment by adding an optional argument after the line end; e.g. \\[-5mm] instead of just \\. You could also try using \smash (see page 55 of the Not So Short Introduction, or sections 2 & 3 of A complement to \smash, \llap, and \rlap for details).

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