# Theta as the zero vector?

1. Feb 18, 2012

### TheTangent

I'm looking at a Linear Algebra book that is using the greek letter θ for the zero vector. And the book has other bold letters, so it can't be that they simply could not make a bold zero.

Has anyone seen such a usage before?

2. Feb 21, 2012

### Deveno

sure. one of the reasons why, is because the 0-vector in a vector space might be rather "unusual". for example, the following is a vector space:

V = R+ = {x in R: x > 0}

the vector sum of x and y is defined to be xy,

the scalar product of a real number c, and a vector x is defined to be: xc.

in this vector space, the 0-vector is the real number 1.

3. Feb 22, 2012

### dx

It done so that you don't get confused between the number 0 and the vector 0.