Array functions ☆
Let M be an array, i be a numeric expression below.

LBOUND(M,i) | The lower bound of the i-th dimension.
UBOUND(M,i) | The upper bound of the i-th dimension.
SIZE(M,i) | The number of the i-th subscripts.
SIZE(M) | The number of current elements.
MAXSIZE(M) | The upper limit of the number of elements.

Example 1.
`DIM A(8,9)`
yields
lbound(A,1)=1, lbound(a,2)=1, ubound(a,1)=8, ubound(a,2)=9
size(A,1)=8, size(A,2)=9, size(A)=72, maxsize(A)=72
if no OPTION BASE exists.
Example 2.

    10 DIM a(10)
    20 MAT a=ZER(5)

yields SIZE(a)=5，MAXSIZE(a)=10.
if no OPTION BASE exists.
If M is 1-dimensional, the following abbreviations are allowed.

LBOUND(M) | The lower bound of the subscript of M.
UBOUND(M) | The upper bound of the subscript of M.

DET-function
Let M be a 2-dimensional array.
DET(A) The determinant of A
If A is not square, an exception shall be caused on execution.
DOT-function
Let A,B be 1-dimensional arrays
DOT(A,B) The dot (inner) product of A and B.
If the size of A and B are different, an exception shall be caused on execution.