Martin DeMello wrote:

>ibotty <me / ibotty.net> wrote:
>  
>
>>before i spent to many words describing something so simple:
>>
>>say, i have:
>>a = [1,2,3] and b = [4,5,6]
>>and i want to get another array, with c[ix] = a[ix] * b[ix].
>>(i want to get c = [4,10,18])
>>
>>is there a builtin function in array.rb (that i have missed).
>>    
>>
>
>Not quite, but for parallel traversing made easier
>
>a.zip(b).map {|i, j| i*j}
>
>martin
>
>
>  
>
But isn't that the wrong answer?
I thought that [1, 2, 3] * [4, 5, 6] would be:
[ [4, 5, 6],
  [8, 10, 12],
  [12, 15, 18]
]  or some such (I might have reversed the arguments--and I don't think 
it's commutative.  [Admittedly, it's been a few decades since I did such 
math.]).  And if you meant the dot product rather than the cross 
product, you would get a scalar.