Language Reference
The ELEMENT function returns a matrix that is the same shape as x. The return value indicates which elements of x are elements of y. In particular, if A = element(x, y), then
![\[ A_ i = \left\{ \begin{array}{ll} 1 & \mbox{if}~ x_ i \in y \\ 0 & \mbox{otherwise} \end{array} \right. \]](images/imlug_langref0275.png){kind=small}
The arguments are as follows:
- x
-
specifies a matrix of elements to test for membership.
- y
-
specifies a set.
If the intersection between x and y is empty, then the ELEMENT function returns a zero matrix. If x is a proper subset of y, then the ELEMENT function returns a matrix of ones. In general, the ELEMENT function returns 1 for elements in the intersection of x and y, as shown in the following statements:
x = {0, 0.5, 1, 1.5, 2, 2.5, 3, 0.5, 1.5, 3, 3, 1};
set = {0 1 3}`;
b = element(x, set);
n = sum(b); /* number of elements of X that are in SET */
idx = t(loc(b)); /* indices of elements of X that are in SET */
values = x[idx]; /* values of elements of X that are in SET */
print n idx values;