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This resource provides an in-depth exploration of matrices, including definitions, types, and fundamental operations. It covers essential matrix types such as row, column, square, symmetric, diagonal, and identity matrices. Additionally, it explains matrix operations including addition, subtraction, multiplication, and the use of scalar multiplication. The resource further discusses the application of matrices in solving simultaneous equations, as well as matrix inversion methods and the Gauss-Jordan elimination technique. A must-read for students and professionals in mathematics and engineering.
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Aij i = row j = column Definition of a Matrix A [ A ]
a11 a12 a13 … … a1n a21 a22 a23 … … a2n … … … aij … … am1 am2 am3 … … amn Definition of a Matrix
a11 a12 a13 … … a1n a21 a22 a23 … … a2n … … … aij … … am1 am2 am3 … … amn size m x n Size of a Matrix
Size of a Matrix 5 21 3 -7 40 -6 19 23 -8 12 50 22 size 3 x 4
Row Matrix [ B ] m = 1 [ 50 -3 -27 35 ]
{D} n = 1 -10 33 -6 15 {-10 33 -6 15} Column Matrix
a11 a12 a13 … … a1n a21 a22 a23 … … a2n … … … aij … … an1 an2 an3 … … ann size m x n 5 21 3 40 -6 19 -8 12 50 size 3 x 3 Square Matrix m = n
a11 a12 a13 … … a1n a21 a22 a23 … … a2n … … … aij … … an1 an2 an3 … … ann 5 21 3 40 -6 19 -8 12 50 5, -6, and 50 are diagonal elements Main Diagonal i = j a11 a22 aij, …, …, ann
a11 a12 a13 … … a1n a21 a22 a23 … … a2n … … … aij … … an1 an2 an3 … … ann Symmetric Matrix aij = aji a12 = a21, a13 = a31, … a1n = an1
Symmetric Matrix 5 21 -3 21 6 19 -8 19 50 21, -3, and 19 are off-diagonal elements
Diagonal Matrix aij = 0, for a j a11 0 0 … … 0 0 a22 0 … … 0 … … … aij … … 0 0 0 … … 0 a12 = a21 = 0, a13 = a31 = 0, … a1n = an1= 0
0 0 0 • 0 6 0 0 • 0 0 19 0 • 0 0 0 21 Diagonal Matrix
1 0 0 … … 0 0 1 0 … … 0 … … … aij … … 0 0 0 … … 1 Unit or Identity Matrix aij = 1, for i = j aij = 0, for i j a12 = a21 = 0, a13 = a31 = 0, … a1n = an1= 0
1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 null matrix aij =0 Unit or Identity Matrix
5 21 -3 A = 21 6 19 -8 19 50 5 21 -3 B = 21 6 19 -8 19 50 Equality A = B Aij = Bij
5 2 A = 2 6 -8 1 5 21 B = 21 6 -8 19 Addition and Subtraction [A] + [B] = [C] Aij + Bij = Cij
10 23 A+B = C = 23 12 -16 20 0 -19 A-B = C = -19 0 0 -18 Addition and Subtraction
5 2 A = 2 6 -8 1 15 6 B = 6 18 -24 3 Multiplication by ScalarScalar c, x [A] c = 3 c A = B
-1 5 2 3 6A = B = 7 -3 4 –8 9 18 -43 51 C = 2 45 -69 Multiplication of Matrices Conformable [A] (m x n) x [B] (n x s) = [C] (m x s) Aik x Bkj = C ij Cij = Ai1B1j +ai2B2j+ … + AinBnj Cij = AikBkj for k = 1 to n
2 3 6 B = 4 –8 9 -1 5 18 -43 51 A = C = 7 -3 2 45 -69 Manual Multiplication
Application to Simultaneous Equations a11x1 + a12x2 + a13x3 = P1 a12x2 + a22x2 + a23x3 = P2 a12x3 + a23x2 + a33x3 = P3 2x1 – 5x2 + 4x3 = 44 3x1 + 1x2 + -8x3 = -35 4x1 – 7x2 – 1x3 = 28
Application to Simultaneous Equations a11 a12 a13 x1 P1 a12 a22 a23 x2 = P2 a12 a23 a33 x3 P3
2 -5 4 x1 44 3 1 -8 x2 = -35 4 -7 -1 x3 -28 [A] {x} = {P} NOTES: [A] [B] [B] [A] A B C = (AB) C = A (BC) A (B + C) = AB + AC [A] [0] = [0], [0] [A] = [0] Application to Simultaneous Equations
1 -2 A = 3 4 -2 1 A-1 = -1.5 0.5 Inverse of a Square Matrix Inverse of [A] = [A-1] [A-1] [A] = [I][A] [A-1] = [I]
Inverse of Square Matrix 1 0 A A-1 = 0 1
Transpose of a Matrix aijT = aji a11 a21 a31 … … an1 a12 a22 a32 … … an2 … … … aji … … a1n a2n a3n … … ann
5 12 -3 18 21 6 19 16 -3 15 50 17 5 21 -3 12 6 15 -3 19 50 18 16 17 Transpose of a Matrix A (3 x 4) , AT(4 x 3)
3 5 -1 ¦ 2 -2 4 7 ¦ 9 6 1 3 ¦ 4 1 8 -5 2 -3 6 7 -1 Partitioning of Matrices [A] [B]
Partitioning of Matrices A11 ¦ A12 A = -----¦------- A21 ¦ A22 B = B11 ------ B21
Partitioning of Matrices B11 B = ------ B21 A11 | A12 A11B11+A12B21 A= ---------------- AB= A21 | A22 A21B11+A22B21
19 28 A11B11 = -43 34 14 -2 A12B21 = 63 -9 Partitioning of Matrices A21B11 = [ -8 68 ] A22B21 = [ 28 -4 ]
Partitioning of Matrices A11B11+A12B21 AB = A21B11+A22B21 19 28 + 14 -2 -6 26 AB = -43 34 + 63 -9 = 20 25 [-8 68 ] + [28 -4] 20 64
Solution of Simultaneous Equations by Gauss-Jordan Method 2x1 – 5x2 + 4x3 = 44 3x1 + x2 - 9x3 = -35 4x1 – 7x2 - x3 = 28 x1 – 2.5x2 + 2x3 = 22 3x1 + x2 - 8x3 = -35 4x1 - 7x2 - x3 = 28
Solution of Simultaneous Equations by Gauss-Jordan Method x1 – 2.5x2 + 2x3 = 22 8.5x2 - 14x3 = -101 3x2 - 9x3 = -60 x1 – 2.5x2 + 2x3 = 22 x2 - 1.647x3 = -11.882 3x2 - 9x3 = -60
Solution of Simultaneous Equations by Gauss-Jordan Method x1 – - 2.118x3 = -7.705 x2 - 1.647x3 = -11.882 - 4.059x3 = -24.354 x1 + 2.118x3 = - 7.705 x2 - 1.647x3 = -11.882 x3 = 6 x1 = 5 x2 = -2 x3 = 6
Solution of Simultaneous Equations by Gauss-Jordan Method Check: 2(5) - 5(-2) + 4(6) = 44 3(5) +1(-2) - 8(6) = -35 4(5) - 7(-2) - 1(6) = 28
Matrix Inversion [A] {x} = {C} [A] [A] {x} = [A]-1 {C} [A] [A] = [I] {x} = [A] {C} [A ¦ I ] { x ¦ -C }= 0 -1 -1 -1
Matrix Inversion [I ¦ B ] { x ¦ -C }= 0 {x} - [B] [C] = 0 {x} = [B] [C] [B] = [A] -1
Method of Successive Transformations 2 4 3 ¦ 1 0 0 1 -2 0 ¦ 0 1 0 -1 -4 5 ¦ 0 0 1 1 2 1.5 ¦ 0.5 0 0 1 -2 0 ¦ 0 1 0 -1 -4 5 ¦ 0 0 1
Method of Successive Transformations 1 2 1.5 ¦ 0.5 0 0 0 -4 -1.5 ¦ -0.5 1 0 -1 -4 5 ¦ 0 0 1 1 2 1.5 ¦ 0.5 0 0 0 -4 -1.5 ¦ -0.5 1 0 0 -2 6.5 ¦ 0.5 0 1
Method of Successive Transformations 1 2 1.5 ¦ 0.5 0 0 0 1 0.375 ¦ 0.125 -0.25 0 0 -2 6.5 ¦ 0.5 0 1 1 2 1.5 ¦ 0.5 0 0 0 1 0.375 ¦ 0.125 -0.25 0 0 0 7.25 ¦ 0.75 -0.5 1
Method of Successive Transformations 1 2 1.5 ¦ 0.5 0 0 0 1 0.375 ¦ 0.125 -0.25 0 0 0 1 ¦ 0.1034 -0.06897 0.1379 1 2 1.5 ¦ 0.5 0 0 0 1 0 ¦ 0.0862 -0.2241 -0.0517 0 0 1 ¦ 0.1034 -0.06897 0.1379
Method of Successive Transformations 1 2 0 ¦ 0.3449 0.1034 -0.2069 0 1 0 ¦ 0.0862 -0.2241 -0.0517 0 0 1 ¦ 0.1034 -0.06897 0.1379 1 0 0 ¦ 0.1725 0.5516 -0.1035 0 1 0 ¦ 0.0862 -0.2241 -0.0517 0 0 1 ¦ 0.1034 -0.06897 0.1379
Method of Successive Transformations 0.1725 0.5516 - 0.1035 A-1 = 0.0862 - 0.2241 - 0.0517 0.1034 - 0.06897 0.1379
Cholesky Decomposition Lower Triangular matrix [L] l11 0 0 . . . . 0 l21 l22 0 . . . . 0 l31 l32 l33 0 . . . 0 . . . . . . . . . . . . . . . . ln1 . . . . . . lnn
Cholesky Decomposition [A] = [L] [L]T [B] = [L] [A] = ( [L] [L] ) [A] = [B] [B] -1 -1 T -1 -1 T
Cholesky Decomposition Elements of [L]: l = 0 for i<j l = (A - ∑l ) l = (A - ∑l l )/l for i>j Summation ∑ from r=1 to j-1 ij 2 1/2 ir ij ii ij ij ir jr
Cholesky Decomposition Elements of [B]: b = 0 for i<j b = 1/l b = -(∑l l )/l or i>j Summation ∑ from r=1 to i-1 ij ii ii ij rj ii ir
Cholesky Decomposition Example: 2 1 1 1 1.5 2 1 2 6.75