Scalars, Vectors, and Matrices
Mathematica represents matrices and vectors using lists. Anything that is not a list Mathematica considers as a scalar.
A vector in Mathematica consists of a list of scalars. A matrix consists of a list of vectors, representing each of its rows. In order to be a valid matrix, all the rows must be the same length, so that the elements of the matrix effectively form a rectangular array.
|VectorQ[expr]||give True if expr has the form of a vector, and False otherwise|
|MatrixQ[expr]||give True if expr has the form of a matrix, and False otherwise|
|Dimensions[expr]||a list of the dimensions of a vector or matrix|
Functions for testing the structure of vectors and matrices.
has the form of a vector.
Anything that is not manifestly a list is treated as a scalar, so applying VectorQ
For a vector, Dimensions
gives a list with a single element equal to the result from Length
This object does not count as a matrix because its rows are of different lengths.