<<peeters` ;
peeters`setGitDir[ "blogit" ]

(*$Assumptions = a > 0 ;*)
Integrate[ 1/(a - u^2), {u, -Infinity, Infinity}]

Clear[s]
s = Sum[ 1/(a - b^2 u^2), {u, -Infinity, Infinity}]  
s /. a -> "E" /. b -> ℏ^2/(2m) // TraditionalForm

Clear[p]
p =Plot[{Sqrt[x], Cot[Sqrt[x]]}, {x, 0, 30}, PlotLegends->Placed[{Sqrt[x], TraditionalForm[Cot[Sqrt[x]]]}, {Right, Bottom}]]

peeters`exportForLatex["ps7p2cFig1",p]