_cosh_sqrt

pmrf.models.components.lines.microstrip._cosh_sqrt(x)

\(\cosh\sqrt{x}\), which is entire in \(x\) although \(\sqrt{x}\) is not.

Near \(x = 0\), where the derivative of \(\sqrt{x}\) is infinite, it is summed as \(\sum_n x^n / (2n)!\), whose first omitted term is below double precision there.