Computes various error functions (erf, erfc, erfi, erfcx),
including the Dawson integral, in the complex plane, based
on algorithms for the computation of the Faddeeva function
w(z) = exp(-z^2) * erfc(-i*z).
Given w(z), the error functions are mostly straightforward
to compute, except for certain regions where we have to
switch to Taylor expansions to avoid cancellation errors
[e.g. near the origin for erf(z)].
w_of_z, Faddeeva's scaled complex error function
Computes various error functions (erf, erfc, erfi, erfcx), including the Dawson integral, in the complex plane, based on algorithms for the computation of the Faddeeva function w(z) = exp(-z^2) * erfc(-i*z). Given w(z), the error functions are mostly straightforward to compute, except for certain regions where we have to switch to Taylor expansions to avoid cancellation errors [e.g. near the origin for erf(z)].