From the following minimal example:
DefManifold[M, 4, IndexRange[a, q]]
DefMetric[-1, met[-a, -b], CD, PrintAs -> "g"]
DefChart[cartesian, M, {0, 1, 2, 3}, {t[], x[], y[], z[]},
FormatBasis -> {"Partials", "Differentials"}, ChartColor -> Red]
flatmetriccart =
CTensor[DiagonalMatrix[{-1, 1, 1, 1}], {-cartesian, -cartesian}, 0];
MetricInBasis[met, -cartesian, flatmetriccart]
Should the inverse metric not be fully defined by requiring it to give the identity when multiplying in the metric? Instead I get the algebraic term:
met[{-0, -cartesian}, {-0, -cartesian}] // ToValues
met[{0, cartesian}, {0, cartesian}] // ToValues
Out: -1
Out: met[{0, cartesian}, {0, cartesian}]
Cheers, thanks all :)