1. Auto detect the matrix type ?
`[[-5,-8,0],[3,5,0],[1,2,-1]]`
Solution:
A matrix, in which number of rows and number of columns are equal, is called a square matrix.
`A` | = | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
The number of rows(3) and number of columns(3) are equal, So `A` is a square matrix
A square matrix `A`, such that `|A| != 0`, is called nonsingular matrix.
`A` | = | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
`|A|` | = | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
`=-5 xx (5 × (-1) - 0 × 2) +8 xx (3 × (-1) - 0 × 1) +0 xx (3 × 2 - 5 × 1)`
`=-5 xx (-5 +0) +8 xx (-3 +0) +0 xx (6 -5)`
`=-5 xx (-5) +8 xx (-3) +0 xx (1)`
`= 25 -24 +0`
`=1`
Here, `|A| != 0`, so `A` is nonsingular matrix
A square matrix `A` is called an involutary matrix, if `A^2 = I` where `I` is the identity matrix.
`A` | = | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
`A×A` | = | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
| × | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
= | | `-5×-5-8×3+0×1` | `-5×-8-8×5+0×2` | `-5×0-8×0+0×-1` | | | `3×-5+5×3+0×1` | `3×-8+5×5+0×2` | `3×0+5×0+0×-1` | | | `1×-5+2×3-1×1` | `1×-8+2×5-1×2` | `1×0+2×0-1×-1` | |
|
= | | `25-24+0` | `40-40+0` | `0+0+0` | | | `-15+15+0` | `-24+25+0` | `0+0+0` | | | `-5+6-1` | `-8+10-2` | `0+0+1` | |
|
= | | `1` | `0` | `0` | | | `0` | `1` | `0` | | | `0` | `0` | `1` | |
|
Here `A^2 = I`, so `A` is an involutary matrix
A square matrix `A` is called a periodic matrix, if `A^m = A` for some positive integer m.
`A` | = | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
`A×A` | = | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
| × | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
= | | `-5×-5-8×3+0×1` | `-5×-8-8×5+0×2` | `-5×0-8×0+0×-1` | | | `3×-5+5×3+0×1` | `3×-8+5×5+0×2` | `3×0+5×0+0×-1` | | | `1×-5+2×3-1×1` | `1×-8+2×5-1×2` | `1×0+2×0-1×-1` | |
|
= | | `25-24+0` | `40-40+0` | `0+0+0` | | | `-15+15+0` | `-24+25+0` | `0+0+0` | | | `-5+6-1` | `-8+10-2` | `0+0+1` | |
|
= | | `1` | `0` | `0` | | | `0` | `1` | `0` | | | `0` | `0` | `1` | |
|
`(A^2)×A` | = | | `1` | `0` | `0` | | | `0` | `1` | `0` | | | `0` | `0` | `1` | |
| × | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
= | | `1×-5+0×3+0×1` | `1×-8+0×5+0×2` | `1×0+0×0+0×-1` | | | `0×-5+1×3+0×1` | `0×-8+1×5+0×2` | `0×0+1×0+0×-1` | | | `0×-5+0×3+1×1` | `0×-8+0×5+1×2` | `0×0+0×0+1×-1` | |
|
= | | `-5+0+0` | `-8+0+0` | `0+0+0` | | | `0+3+0` | `0+5+0` | `0+0+0` | | | `0+0+1` | `0+0+2` | `0+0-1` | |
|
= | | `-5` | `-8` | `0` | | | `3` | `5` | `0` | | | `1` | `2` | `-1` | |
|
Here `A^3 = A`, so `A` is a periodic matrix of period 2
This material is intended as a summary. Use your textbook for detail explanation.
Any bug, improvement, feedback then