Concept
Basis
2 essays name this object, across one field. What follows is each of them, and the objects they name alongside it.
Also named here as determinant — the same set of essays touches all of them, so they are one junction rather than several.
A matrix is a picture of what happens to the grid
Four numbers in a box is not an object anyone has intuitions about. The same four numbers, shown as an instruction for redrawing the plane, are.
The directions a map leaves alone
Almost every arrow comes out of a transformation pointing somewhere else. A few come out pointing exactly where they went in, only longer or shorter. Those few decide nearly everything the map does.
Named alongside it
The objects these essays reach for when they reach for this one.
DeterminantMatrixAreaCharacteristic polynomialDiagonalisationEigenvalueEigenvectorInvariant directionOrientationOrthogonalityRankSingular matrix