This site describes solve-engine as it is on main: 2.43.0, which npm does not have yet. npm installs 2.40.0, so a page may show an answer that version does not give yet.
MatrixEntry
type MatrixEntry = number | boolean | SymbolicNode;Defined in: packages/engine/src/vm/Value.ts:17
A single matrix cell. boolean covers element-wise comparison results
([1,6;3,8] < [5,2;7,4] produces a Matrix of booleans, not numbers). A
SymbolicNode cell is a free-variable algebraic entry, e.g. s = [sx,0,0;0,sy,0;0,0,1] where sx/sy are never assigned, so those
cells store a real SymbolicNode (a bare var node initially) rather
than degrading to 0. See MatrixOps.ts’s entryToSymbolic()/
symbolicToEntry() for the two-way conversion every symbolic-aware
matrix op (multiply, inverse, determinant) uses.