title: MDX function to find if a Member IsMemberOf a set
body: <p>This feels like a really basic question, because it's a really basic function I'm looking for.</p>
  
  <p>I know you can do this:</p>
  
  <pre><code>([Dimension].CurrentMember IS [Dimension].[AParticularMember])
  </code></pre>
  
  <p>and you get a logical 1 or 0 as the function value.</p>
  
  <p>But how do you do this kind of thing, without concatenating IS functions in a whole lot of ugly ORs:</p>
  
  <pre><code>([Dimension].CurrentMember ISAMEMBEROF 
       {[Dimension].[AMember],[Dimension].[AnotherMember],[Dimension].[YetAnotherMember]}
  )
  </code></pre>
  
  <p>?</p>
  
  <p>This is really basic set operations, in one dimension only, but I just can't find the damn function that does it.  I tried this:</p>
  
  <pre><code>NOT(ISEMPTY(INTERSECT([Dimension].CurrentMember,
  {[Dimension].[AMember],[Dimension].[AnotherMember],[Dimension].[YetAnotherMember]})))
  </code></pre>
  
  <p>but it returned True for every dimension member.  I'm guessing this is because what is going into the ISEMPTY function is not the dimension member, but the tuple</p>
  
  <pre><code>([Dimension].CurrentMember,[AnotherDimension].DefaultMember,  
  [YetAnotherDimension].DefaultMember,... ,Measures.DefaultMember)
  </code></pre>
  
  <p>does the kind of function I'm looking for exist in MDX?</p>