Question: How to do that a conditional es evaluated "globally" with `IF`?

Dear friends,


I can compute,  with Maple 14, summe1:

> summe1= sum( sum( (`if`(1 < x , 1, 0))*   x*j, x=0..2), j=0..2);


However, when I modify  summe1 to summe2, I get an error message:


> summe2= sum( sum( (`if`(1 < x+j , 1, 0))*  (x*j), x=0..2), j=0..2);


> Error, (in eval/if) cannot determine if this expression is true or false: 1 < j


Is there some way to avoid this error? ( I do mean, that the conditiona IF identify the values that J will take).


Kind regards,



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