rontolisp:quantized-matrix-p

(rontolisp:quantized-matrix-p object)

t when object is a quantized matrix (rontolisp:quantize), nil for anything else -- a packed float array included, since a quantized matrix is not an array. (typep object 'rontolisp:quantized-matrix) and typecase answer the same question through the type name.

Works on every backend: on the two WASM backends no quantized matrix can exist, so the predicate is nil there.