* themselves. For them, an additional interface exists, consisting of
* the functions
* @code
- * void step (VECTOR& dst, const VECTOR& src) const;
- * void Tstep (VECTOR& dst, const VECTOR& src) const;
+ * void step (VECTOR& dst, const VECTOR& rhs) const;
+ * void Tstep (VECTOR& dst, const VECTOR& rhs) const;
* @endcode
*
* Here, $src$ is a residual vector and $dst$ is the iterate that is
* supposed to be updated. In other words, the operation performed by
* these functions is
- * $dst = dst - P^{-1} src$ and $dst = dst - P^{-T} src$. The
+ * $dst = dst - P^{-1} (A dst - rhs)$ and $dst = dst - P^{-T} (A dst - rhs)$. The
* functions are called this way because they perform <i>one step</i>
- * of a fixed point iteration.
+ * of a fixed point (Richardson) iteration. Note that preconditioners
+ * store a reference to the original matrix $A$ during initialization.
*
* @ingroup LAC
* @ingroup Matrices