Column Space - Relation To The Left Null Space

Relation To The Left Null Space

The left null space of A is the set of all vectors x such that xTA = 0T. It is the same as the null space of the transpose of A. The left null space is the orthogonal complement to the column space of A.

This can be seen by writing the product of the matrix and the vector x in terms of the dot product of vectors:

where c1, ..., cn are the column vectors of A. Thus x = 0 if and only if x is orthogonal (perpendicular) to each of the column vectors of A.

It follows that the null space of is the orthogonal complement to the column space of A.

For a matrix A, the column space, row space, null space, and left null space are sometimes referred to as the four fundamental subspaces.

Read more about this topic:  Column Space

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