member( x, M ) returns true if x is a member of the MultiSet M, false otherwise

Note: member( x, M ) is equivalent to evalb( x in M ) and also equivalent to evalb( M[x] <> 0 ).

Note: As a MultiSet is unordered, attempting to use the three-argument form of the member command, as in member( x, M, 'k' ) will result in an error.

$M≔\mathrm{MultiSet}\left(a=2\&comma;b=5\right)$

$M≔\left\{\left[a\&comma;2\right]\&comma;\left[b\&comma;5\right]\right\}$

$\mathrm{member}\left(b\&comma;M\right)$

$\mathrm{true}$

$\mathrm{member}\left(c\&comma;M\right)$

$\mathrm{false}$

$\mathrm{evalb}\left(a\mathbf{in}M\right)$

$\mathrm{true}$

$\mathrm{member}\left(a\&comma;M\&comma;'k'\right)$

Error, index of member is undefined

The MultiSet/member command was introduced in Maple 2016.

For more information on Maple 2016 changes, see Updates in Maple 2016.