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MemberQ

MemberQ
returns True if an element of list matches form, and False otherwise.
MemberQ
tests all parts of list specified by levelspec.
  • form can be a pattern.
  • The first argument of MemberQ can have any head, not necessarily List.
  • MemberQ immediately tests whether any expression in list matches form; Element asserts that x is an element of the symbolic domain dom.
  • MemberQ uses standard level specifications:
nlevels through n
Infinitylevels through Infinity
{n}level n only
{n1,n2}levels through
  • The default value for levelspec in MemberQ is .
  • A positive level n consists of all parts of expr specified by n indices.
  • A negative level -n consists of all parts of expr with depth n.
  • Level consists of numbers, symbols, and other objects that do not have subparts.
  • Level corresponds to the whole expression.
  • With the option setting Heads->True, MemberQ looks at heads of expressions and their parts.
Test whether is a member of a list:
Test whether is a member of a list:
In[1]:=
Click for copyable input
Out[1]=
MemberQ works with patterns:
Test down to level :
MemberQ normally only tests level :
Test whether is ever equal to 1 modulo 7:
MemberQ tests for structural matches, not numerical equality:
MemberQ does not test for subsequences:
FreeQ does:
MemberQ by default only operates at level :
Include level :
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