Given a 3D vector, can you get the X coordinate without using 3D Vector to Scalar or any other conversion node? (Not that there’s anything wrong with using a conversion node.)
Hint: ||A||*||B||*adjacent/hypotenuse
Answer
eX-SI
ICE, scripting, and other tech stuff about Softimage aka XSI
eX-SI 
Wouldn’t it be simpler/faster to multiply the vector by (1,0,0) and plug it into the “Value 2” of your Build Array?
Yes, you could simply use Multiply.
But I don’t know if it would be faster, because presumably that is exactly what the Dot Product node is doing 🙂
Would have to test it. In such a case, where we have 2 nodes doing the same job as one low-level node, isn’t it faster to use a low level node that is written to do that job exactly?