Array matching

I have 2 arrays that i'd like to compare values and create a child that contains matching values (and I'd like to do this the fastest way possible).

Example:

A = [1;0;-1;0;0;0;1]
B = [0;1;-1;0;1;0;1]

child = [0;0;-1;0;0;0;1]

Your help is greatly appreciated! Thank you.

Answer 1

[Geoff]

child = A;
child(A ~= B) = 0;

[Richard Brown]

pah! pathetic! None of this two line nonsense!

child = A .* (A == B)

[Jan]

Even an incorrect answer would not be "nonsense".

I assume Geoff's solution is faster than Richard's, because it does not need the implicit conversion of the logical array "(A==B)" to a double and perform LENGTH(A) floating point multiplications.

[James Tursa]

child = A .* (A == B) will produce NaN values instead of the desired 0 if the A element is inf and the B element is not inf.

[Geoff]

Erm, thanks Richard. I'm a computer scientist, not a mathematician.

[Richard Brown]

I'm guessing from these responses that I should probably point out that I was joking ... :)

If I had thought my solution was better, I would have posted it as a separate answer

[James Tursa]

Maybe some regulars might have recognized this, but it is likely newbies would not. Hence my comment.

[Richard Brown]

Fair point. The same might also be true of

non-native English speakers who may have

thought I was being genuinely critical of

dear Geoff :-)

[Geoff]

Hey it even fooled me... I was under a bit of pressure and lost my sense of humour for a couple of days. =)

[Jan]

I frequently confuse humor and humerus. Therefore I thank you for your clarifications.

Is the OP still interested in the solution?