
#include nagmk26.h

$$d=c+\sum _{i=1}^{n}{a}_{i}{b}_{i}\text{.}$$ 
On entry,  ${\mathbf{istepa}}\le 0$, 
or  ${\mathbf{istepb}}\le 0$. 
On entry,  ${\mathbf{isizea}}<\left({\mathbf{n}}1\right)\times {\mathbf{istepa}}+1$, 
or  ${\mathbf{isizeb}}<\left({\mathbf{n}}1\right)\times {\mathbf{istepb}}+1$. 
$$A=\left(\begin{array}{lrc}1& i& 1\\ \phantom{}2+3i& i& 2i\\ \phantom{}0& 1i& 12i\end{array}\right)\text{, \hspace{1em}}{\mathbf{b}}=\left(\begin{array}{r}i\\ 1i\\ i\end{array}\right)\text{.}$$ 