When Should Vectors Be Columns or Rows in Matrices?

[astrokat11]

I'm in a linear algebra course and I thought I understood the idea of putting vectors into matrices, but now I seem to be confused. When do you put the vectors into columns and when do you put them into rows? Also, what is the definition of a standard matrix and how do you compute it?
Thank you,

AstroKat

 

[Hurkyl]

When do you put the vectors into columns

When you want the vectors in the columns.

and when do you put them into rows?

When you want the vectors in the rows.

Also, what is the definition of a standard matrix and how do you compute it?

You'll need to give more context for that one.