Returns the indices of the elements of a vector which fall into a specified category
x (Nx1 vector) – data
v (scalar or 2x1 vector) –
If scalar, the function returns the indices of all elements of x equal to v. If 2x1, then the function returns the indices of all elements of x that fall into the range:\[v < x <= v\]
If v is scalar, it can contain a single missing to specify the missing value as the category.
y (Lx1 vector) – Indices of the elements of x which fall into the category defined by v. It will contain error code 13 if there are no elements in this category.