Types

Qhronology’s underlying functionality takes advantage of a few bespoke type aliases, which are summarized in the table below.

Table 3 Internal type aliases.

Alias	Description	Definition
num	Numerical scalars	numbers.Number | numpy.generic | sympy.Basic
sym	SymPy scalar symbols	sympy.matrices.expressions.matexpr.MatrixSymbol | sympy.matrices.expressions.matexpr.MatrixElement | sympy.core.symbol.Symbol
expr	SymPy scalar expressions	sympy.core.expr.Expr
mat	SymPy dense matrices (mutable)	sympy.matrices.dense.MutableDenseMatrix
arr	NumPy arrays	numpy.ndarray

It may be useful to know that sym is a subtype of expr. In other words, the set of all sym-type objects is a proper subset of the set of all expr-type objects.