Brain smoker ...

[DrD]

This was my challenge of the day:

Find the sum of the absolute values of the products, of all the pairs of numbers, where one is drawn from each of two lists:

Example
a:={2,-3}
b:={4,-5}

This is the goal: (Absolute values of the above): 2*4 + 2*5 +3*4 +3*5 = 45

I tried a few things and came up with this: sum(mat2list(map(a,(a)->ABS(a*b))))

which seems to be my best effort (so far!) If you feel so inclined, can you find other (hp prime) ways, perhaps more efficient in some way?

-Dale-