  \textsc{Lara} is a key-value algebra that aims at unifying linear and
relational algebra with three types of operation abstraction. The study of
\textsc{Lara}'s expressive ability reports that it can represent relational
algebra and most linear algebra operations. However, several essential
computations, such as matrix inversion and determinant, cannot be expressed in
\textsc{Lara}. \textsc{Lara} cannot represent global and iterative computation,
either. This article proposes \textsc{IterLara}, extending \textsc{Lara} with
iterative operators, to provide an algebraic model that unifies operations in
general-purpose computing, like big data, AI, scientific computing, and
database. We study the expressive ability of \textsc{Lara} and
\textsc{IterLara} and prove that \textsc{IterLara} with aggregation functions
can represent matrix inversion, determinant. Besides, we demonstrate that
\textsc{IterLara} with no limitation of function utility is Turing complete. We
also propose the Operation Count (OP) as a metric of computation amount for
\textsc{IterLara} and ensure that the OP metric is in accordance with the
existing computation metrics.
