@Kitonum thanks for that!

Could you just tell me why the extra condition, see below, is made on the list?

(a,b)->a[1]<=b[1]

@Preben Alsholm so simple yet so genius :-). Thanks a lot man!! 

@Preben Alsholm thanks for the fast reply !

So if the three conditions are true then I want maple to use the first equation and if one of them is false maple should use the second equation (the one after  "else")