> mean( { 1/2, 2/3, 3/4, 4/5, 5/6 } ); # set
                                  71
                                  ---
                                  100

> mean( [ a, 2, c, 2.3, e ] ); # list
                     0.8600000000 + a/5 + c/5 + e/5

> mean( Array( [ 1, sin( s ), 3, exp( I*t ), 5 ] ) ); # array
                    9/5 + 1/5 sin(s) + 1/5 exp(t I)

> mean( [ sin(s)^2, cos(s)^2 ] );
                                 2             2
                       1/2 sin(s)  + 1/2 cos(s)

> Normalizer := simplify: # use a stronger normalizer than the default
> mean( [ sin(s)^2, cos(s)^2 ] );
                                  1/2

> mean([]); # empty argument causes an exception to be raised.
Error, (in mean) numeric exception: division by zero