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.
builtinFunctions
const builtinFunctions: Record<number, (args, context?) => Value>;Defined in: packages/engine/src/vm/VMBuiltins.ts:986
Registry of built-in mathematical functions. Indexed by the number pushed as an operand of OpCode.CALL_BUILTIN.