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Matrix Size & Validation
Vector Algebra
What is Vector?
Vector Norm
Unit Vector
Vector Addition
Vector Subtraction
Vector Scalar Multiple
Vector Multiplication
Vector Inner Product
Vector Outer Product
Vector Cross Product
Vector Triple Cross Product
Vector Triple Dot Product
Scalar Triple Product
Orthogonal & Orthonormal Vector
Cos Angle of Vectors
Scalar and Vector Projection
Matrix Algebra
What is a matrix?
Special Matrices
Matrix One
Null Matrix
Matrix Diagonal Is Diagonal Matrix?
Identity Matrix
Matrix Determinant
Matrix Sum
Matrix Trace
Matrix Basic Operation
Is Equal Matrix?
Matrix Transpose
Matrix Addition
Matrix Subtraction
Matrix Multiplication
Matrix Scalar Multiple
Hadamard Product
Horizontal Concatenation
Vertical Concatenation
Elementary Row Operations
Matrix RREF
Finding inverse using RREF (Gauss-Jordan)
Finding Matrix Rank using RREF
Matrix Inverse
Is Singular Matrix?
Linear Transformation
Matrix Generalized Inverse
Solving System of Linear Equations
Linear combination, Span & Basis Vector
Linearly Dependent & Linearly Independent
Change of basis
Matrix Rank
Matrix Range
Matrix Nullity & Null Space
Eigen System
Matrix Eigen Value & Eigen Vector
Symmetric Matrix
Matrix Eigen Value & Eigen Vector for Symmetric Matrix
Similarity Transformation and Matrix Diagonalization
Matrix Power
Orthogonal Matrix
Spectral Decomposition
Singular Value Decomposition
Resources on Linear Algebra

Matrix Rank

By Kardi Teknomo, PhD.
LinearAlgebra

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Recalled in the previous topics when we have a set of basis vectors, we can concatenate these vectors into a matrix. Using this matrix, we can also change the basis or the coordinate system. In this page, you will learn more about that augmented matrix.

Suppose we have a matrixMatrix Ranksize Matrix RankbyMatrix Rank. We can imagine this matrix is actually a vertical concatenation of row vectors. A set of row vectors that form a matrix is called row space of the matrix.
Matrix Rank

Similarly, we can imagine the matrix Matrix Rankis actually a horizontal concatenation of column vectors. A set of column vectors that form a matrix is called column space of the matrix.
Matrix Rank

The dimension of row space of a matrix is equal to the dimension of the column space of that matrix. The common dimension of the row space and column space of matrix Matrix Rankis called the rank of matrixMatrix Rank, denoted byMatrix Rank. The rank of Matrix Rankis the number of linearly independent vectors and equal to the dimension of space spanned by those vectors. In other words, rank of Matrix Rank is the number of basis vectors we can form from matrixMatrix Rank.

Performing elementary row operation does not change the row space. To compute the rank of a matrix, we reduce the matrix into reduced row echelon form (RREF) and non-zero rows of the RREF matrix will form the basis for the row space.

The interactive program below produces matrix rank. The computation is based on numerical method of Singular Value Decomposition (SVD). The input is rectangular matrix. Random Example button will provide you with many examples.

Properties

Some important properties of matrix rank are:

  • Transpose operation does not change the rank of a matrixMatrix Rank.
  • Multiplication of a matrix with its transpose does not change the rank of the matrixMatrix Rank.
  • Rank of a matrix size Matrix RankbyMatrix Rank is always less or equal to the minimum size of the matrix. A matrix is said to be of full rank whenMatrix Rank.
  • Let matrix Matrix Rankand Matrix Rankboth are matrices of the same size Matrix RankbyMatrix Rank, not necessarily of full rank, then we have the following
    o   Rank of matrix addition: Matrix Rank
    o   Rank of matrix subtraction: Matrix Rank
  • Let matrix Matrix Rankand Matrix Rankare not necessarily the same size, then we have the following
    o   Rank of matrix product: Matrix Rank
    o   Rank of matrix product compare to summation of rank: Matrix Rank
  • The dimension of the range and the null space of a matrix are related through fundamental relationshipMatrix Rank.
  • A linear system Matrix Rankhas a solution if and only if the rank of the coefficient matrix is equal to the rank of the augmented matrixMatrix Rank. When non-homogeneous system is not full rank or when the rank of the matrix coefficients is less than the rank of the augmented matrix coefficients and the vector constants Matrix Rankthen the system is usually inconsistent with no possible solution. It is still possible to find the approximate solution using generalized inverseMatrix Rank.
  • A matrix Matrix Rankhas a left inverse Matrix Rankif and only if its rank equals its number of columnsMatrix Rank. If matrix Matrix Rank has more columns than rows (Matrix Rank), it cannot have a left inverse.
  • A matrix Matrix Rankhas a right inverseMatrix Rank if and only if its rank equals its number of rowsMatrix Rank. If matrix Matrix Rank has more rows than columns (Matrix Rank), it cannot have a right inverse.
  • A matrix Matrix Rankhas an inverse Matrix Rank (non-singular) if and only if it is a square matrix and the rank of the matrix is full, that is the rank equals to the number of rows (or columns) Matrix Rank. If matrix Matrix Rank is not square (Matrix Rank), it cannot have a two-sided inverse. Equivalently, the determinant of the matrix is non-zeroMatrix Rank.

See also: rank through RREF, matrix range, matrix nullity and null space, solving system linear equations

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This tutorial is copyrighted.

Preferable reference for this tutorial is

Teknomo, Kardi (2011) Linear Algebra tutorial. http:\\people.revoledu.com\kardi\ tutorial\LinearAlgebra\

 

 
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