Online Algebra Calculator
Many of users do not use powerful Maxima computer algebra system for systematic work, but for ad hoc algebraic calculations – equations, functions, matrixes, etc. only. To do this job, it is not useful to download the whole application from a web site.
Function: subset (<a>, <f>) Returns the subset of the set <a> that satisfies the predicate <f>.

subset returns a set which comprises the elements of <a> for which <f> returns anything other than false. subset does not apply is to the return value of <f>.
subset complains if <a> is not a literal set.
See also partition_set.
Examples:
(%i1) subset ({1, 2, x, x + y, z, x + y + z}, atom);
(%o1) {1, 2, x, z}
(%i2) subset ({1, 2, 7, 8, 9, 14}, evenp);
(%o2) {2, 8, 14} There are also some inexact matches for subset. Try ?? subset to see them.
(%o1) true (%i2)