For example ```rust
tex_expr!(r"\frac\pi 3 (1-\cos^2\psi)^2");
Gets expanded zu something close to
rust
std::f64::consts::PI / 3f64 * ( 1f64 - psi.cos().powi(2) ).powi(2);
Similarly,
rust
tex_equation!(r"x=\frac\pi 3 (1-\cos^2\psi)^2");
gets expanded to
rust
let x = std::f64::consts::PI / 3f64 * ( 1f64 - psi.cos().powi(2) ).powi(2);
If, for example, `myinput.tex` contains
latex
Other \LaTeX code
\begin{align}
x=\frac\pi 3 (1-\cos^2\psi)^2
\end{align}
Other \LaTeX code
\begin{align}
a=b+c
\end{align}
Other \LaTeX code
then
rust ignore
fromlatexfile!("myinput.tex");
gets expanded to
rust
let x = std::f64::consts::PI / 3f64 * ( 1f64 - psi.cos().powi(2) ).powi(2); let a = b + c; ```