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Comment by sampo | Hacker News Reader

How does adding

    Array(1.0, 2.0, 3.0, 4.0)

and

    Array(4.0, 3.0, 2.0, 1.0)

result in

    Array(1.7302967433402214, 2.547722557505166, 3.3651483716701107, 4.182574185835056)

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Floats are weird and unpredictable like that. You can save yourself an RNG call if you simply add two floats. ;-)

More seriously, the result here really is x + y/norm(y). I would be really interested in knowing what the bug is here. Probably just a C&P error that forgot to update the result, since y is unitized (in-place?) in a call further below.

Is there something wrong in your code? I don't see the effect.

smile> val x = Array(1.0, 2.0, 3.0, 4.0)

x: Array[Double] = Array(1.0, 2.0, 3.0, 4.0)

smile> val y = Array(4.0, 3.0, 2.0, 1.0)

y: Array[Double] = Array(4.0, 3.0, 2.0, 1.0)

smile> x + y

res2: smile.math.VectorAddVector = Array(5.0, 5.0, 5.0, 5.0)

I just quoted the example in the webpage (section "Vector Operations"), I didn't run it myself.

Good eyes :) It should be a c&p error.

Ok, they have fixed the website now.

That does seem very strange.

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