Expert: Steve Holleran - 8/17/2007

Question
Hi there

I am presently (re)learning vectors for the purposes of programming.

In the sites I've looked at teaching about vectors for physics, the notation seems to take into account only one point (p1) while p0 is assumed to be at the origin(?).

In programming though I will need to have both p0 and p1 at explicitly defined points.

What is/are the correct notation(s) for writing a vector that consists of two explicit points? Perhaps you could point me to a page showing this so I can see the types of brackets etc. used.

Thanks!

Answer
Hi Nick,

The main way I've seen this done is using the unit vector notation, where i the the unit vector in the horizontal direction, and j the unit vector in the vertical direction.

Then if P1 is (x1,y1) and P2 is (x2,y2), then the vector

P1P2 = (x2-x1)i + (y2-y1)j

I would just search for "vectors" or "vector algebra" for websites that would help.

Steve Holleran