Cplx is a library of complex and hypercomplex numbers by Cayley-Dickson construction. Examples of hypercomplex numbers include the usual complex numbers, split-complex numbers, dual numbers, and quaternions. The API is tentative, thus the version number 0.0. I'm not yet sure how i want to present these: as now as a bare Cayley-Dickson construction or wrapped somehow, so one writes Complex<Real, Signature> which expands to Complex<Complex<...>, ...>.