## Metric

Makes a two-tensor a metric.

Labels the object as a symmetric tensor, and optionally gives it the
indicated signature through the `signature`parameter.

g_{m n}::Metric(signature=1).
ex:= g_{m n} A^{n p};
eliminate_metric(_);

\(\displaystyle{}g_{m n} A^{n p}\)

g_{m n} A^{n p}

\(\displaystyle{}A_{m}\,^{p}\)

A_{m}^{p}

Objects declared as

`Metric`

can be used to automatically
raise or lower indices using the
`eliminate_metric`

algorithm, as above.