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Question:Sets????

Posted: tomleslie 13836

February 13 2019

You use curly braces, ie '{}' as a container. Within Maple such curly braces designate a set, and Maple will always display sets in "lexicographic" order.

Since order has no meaning for entries in a set, trying to "sort" a set is meaningless. You can only sort lists, Arrays etc where the concept of order meaningful

See the attached for examples of sorting sets, lists, Arrays, and note that sorting of sets doesn't do anything useful

For future reference

This should be a "Question", not a "Post" (and if I knew how to move it I would!)
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  restart;
  alpha:=[2,3,4,5];
#
# Try sorting sets - won't work because
# order is meaningless in a set
#
  sort( {abs(alpha[1]-30),abs(alpha[2]-30),abs(alpha[3]-30),abs(alpha[4]-30)}, `<`);
  whattype(%);
  sort( {abs(alpha[1]-30),abs(alpha[2]-30),abs(alpha[3]-30),abs(alpha[4]-30)}, `>`);
  whattype(%);
#
# Do the same thing with lists, where order is significant
#
  sort( [abs(alpha[1]-30),abs(alpha[2]-30),abs(alpha[3]-30),abs(alpha[4]-30)], `<`);
  whattype(%);
  sort( [abs(alpha[1]-30),abs(alpha[2]-30),abs(alpha[3]-30),abs(alpha[4]-30)], `>`);
  whattype(%);
#
# You can also sort entries in an Array()
#
  sort(Array([abs(alpha[1]-30),abs(alpha[2]-30),abs(alpha[3]-30),abs(alpha[4]-30)]), `<`);
  whattype(%);
  sort(Array([abs(alpha[1]-30),abs(alpha[2]-30),abs(alpha[3]-30),abs(alpha[4]-30)]), `>`);
  whattype(%);