PH curves are parametric polynomial curves for which the norm of
the first derivative is still a polynomial. Introduced by Farouki
and Sakkalis in 1990, they found several applications in
manufacturing, numerical control machines and robotics. Here we
consider their exponential counterparts, based on exponential
polynomials, in order to expand the design options for this class
of curves. The construction of EPH curves revolves on quaternions
with exponential polynomial coefficients, while their evaluation
presents some numerical issues which are addressed by the new
algorithm proposed.