Group 1
J symbol (dollar): $
Monadic case:
Name: shape
Rank: _ (infinite/unbounded) – applies to the entire array y
Definition (simple): $ y is the shape of y (i.e., a list of the lengths of each axis of y).
Definition (precise): $ y returns a numeric list, where the ith element of the list is the length of the ith axis of y, or if y is a scalar then $ y is an empty list (scalars have no axes).
Please also include explanations for your answers to some of the following questions:
What is the shape of a scalar, vector, matrix, rank 3 array?
What is the shape of an empty list?
How do you find the rank of a scalar, vector, matrix, r-array using $ ?
Dyadic case:
Name: reshape
Rank: 1 (left); _ (right) – applies to a vector on the left and the entire array on the right
Definition (simple): x $ y reshapes array y into the shape specified by x.
Definition (precise): x $ y the shape of x $ y is x, siy where siy is the shape of an item of y; x $ y gives a length error if y is empty and x, siy does not contain a zero.
Please also include explanations for your answers to some of the following questions:
Reshape a scalar, vector, matrix?
What happens when (an element of) x is 0?
What happens when x is empty?
What happens when y contains too many elements?
What happends when y contains too few elements?