Starting from an A-stable rational approximation to $\rm{e}^z$ of order $p$, $$r(z)= 1+ z+ \cdots + z^p/ p! + O(z^{p+1}),$$ families of stable methods are proposed to time discretize abstract IVP's of the type $u'(t) = A u(t) + f(t)$. These numerical procedures turn out to be of order $p$, thus overcoming the order reduction phenomenon, and only one evaluation of $f$ per step is required.
翻译:从对$\rm{e}^z$的$p$阶A-稳定有理逼近出发,$$r(z)= 1+ z+ \cdots + z^p/ p! + O(z^{p+1}),$$ 本文提出了一系列稳定方法,用于对形如$u'(t) = A u(t) + f(t)$的抽象初值问题进行时间离散化。这些数值方法被证实具有$p$阶精度,从而克服了阶数降低现象,且每步仅需计算一次$f$。