# Vector notation with parentheses?

Suppose I have a vector $\mathbf{a}=a_x\mathbf{\hat e}_x+a_y\mathbf{\hat e}_y+a_z\mathbf{\hat e}_z$. I want to write $\mathbf{a}$ with parentheses and without the unit vectors. Should I write $$\mathbf{a}=(a_x,a_y,a_z)$$ or $$\mathbf{a}(a_x,a_y,a_z)=(a_x,a_y,a_z)$$?

Are there any differences?

Thanks!

• Usually we write $\mathbf a = (a_x,a_y,a_x)$ for vectors and $P(p_x,p_y,p_z)$ for points. But then, points and vectors are often not distinguished anyway, so I'd say just be consistent with whichever convention you choose. I don't see any reason to write $\mathbf{a}(a_x,a_y,a_z)=(a_x,a_y,a_z)$ though as it's just extra writing that doesn't give any more information. – user137731 Oct 30 '16 at 16:02
• For me, writing a $=(a_x,a_y,a_z)$ is well understood, but the second way you have written may be misconstrued as a being a so-called operator (a function) which maps the vector $(a_x,a_y,a_z)$ to itself. – Matt Oct 30 '16 at 16:12