22. Rank of a Matrix
Matrices play a crucial role in linear algebra, particularly through the concept of rank, which measures the linear independence of rows or columns. Understanding rank is vital for solving linear systems, especially in civil engineering applications such as structural analysis and finite element methods. The chapter outlines various forms of matrices, elementary row operations, methods to determine rank, and the application of rank in assessing the consistency of linear systems.
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What we have learnt
- The rank of a matrix is defined as the maximum number of linearly independent rows or columns.
- Matrices can be transformed into Row Echelon Form (REF) and Reduced Row Echelon Form (RREF) to facilitate the determination of their rank.
- Rank plays a critical role in solving linear systems, with specific implications for consistency and solution nature.
Key Concepts
- -- Rank of a Matrix
- The maximum number of linearly independent rows or columns in a matrix.
- -- Row Echelon Form (REF)
- A matrix is in REF if all nonzero rows are above any rows of zeros and the leading coefficients of nonzero rows are to the right of those above them.
- -- Reduced Row Echelon Form (RREF)
- A matrix in RREF contains leading ones in each nonzero row and each leading one is the only non-zero entry in its column.
- -- Elementary Row Operations
- Operations including row swapping, scalar multiplication, and row addition used to manipulate matrices without changing their rank.
- -- Rouché–Capelli Theorem
- A theorem stating that a system of linear equations is consistent if and only if the rank of the coefficient matrix equals the rank of the augmented matrix.
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