Essential Vocabulary
Here is a link to a list of these terms on Quizlet
Basis
A set of vectors is called a basis of (or a basis of a subspace of ) provided that
- (a)
- (or )
- (b)
- is linearly independent.
Closed under addition
A set is said to be closed under addition if for each element and the sum is also in .
Closed under scalar multiplication
A set is said to be closed under scalar multiplication if for each element and for each scalar the product is also in .
Column space of a matrix
Let be an matrix. The column space of , denoted by , is the subspace of spanned by the columns of .
Coordinate vector with respect to a basis
Let be an ordered basis. Then the coordinate vector is the column vector such that .
Dimension
Let be a subspace of . The dimension of is the number, , of elements in any basis of . We write
Null space of a matrix
Let be an matrix. The null space of , denoted by , is the set of all vectors in such that . It is a subspace of .
Nullity of a matrix
Let be a matrix. The dimension of the null space of is called the nullity of .
Ordered basis
A basis in which the elements appear in a specific fixed order. Establishing an order is necessary because a coordinate vector with respect to a given basis relies on the order in which the basis elements appear.
Rank of a matrix
Let be a matrix. The dimension of the row space of is called the rank of .
Rank-Nullity theorem
Let be an matrix. Then
Row space of a matrix
Let be an matrix. The row space of , denoted by , is the subspace of spanned by the rows of .
Subspace
Suppose that is a nonempty subset of that is closed under addition and closed under scalar multiplication. Then is a subspace of .