Efficient way of finding distance between two 3D points

Question

I am writing a code in C++ and want to compute distance between two points. Question 1:

I have two points P(x1, y1, z1) and Q(x2, y2, z2) , where x,

Answer 1

You might find this article interesting:

http://www.codemaestro.com/reviews/9

It describes how the square root was calculated in the Quake 3 engine, claiming that on some CPU's it ran 4 times as fast as the sqrt() function. Not sure whether it'll give you a performance boost in C++ nowadays - but still an interesting read