57 lines
1.3 KiB
Kotlin
57 lines
1.3 KiB
Kotlin
// version 1.1.3
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typealias Vector = DoubleArray
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typealias Matrix = Array<Vector>
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operator fun Matrix.times(other: Matrix): Matrix {
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val rows1 = this.size
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val cols1 = this[0].size
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val rows2 = other.size
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val cols2 = other[0].size
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require(cols1 == rows2)
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val result = Matrix(rows1) { Vector(cols2) }
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for (i in 0 until rows1) {
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for (j in 0 until cols2) {
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for (k in 0 until rows2) {
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result[i][j] += this[i][k] * other[k][j]
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}
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}
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}
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return result
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}
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fun identityMatrix(n: Int): Matrix {
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require(n >= 1)
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val ident = Matrix(n) { Vector(n) }
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for (i in 0 until n) ident[i][i] = 1.0
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return ident
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}
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infix fun Matrix.pow(n : Int): Matrix {
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require (n >= 0 && this.size == this[0].size)
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if (n == 0) return identityMatrix(this.size)
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if (n == 1) return this
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var pow = identityMatrix(this.size)
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var base = this
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var e = n
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while (e > 0) {
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if ((e and 1) == 1) pow *= base
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e = e shr 1
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base *= base
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}
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return pow
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}
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fun printMatrix(m: Matrix, n: Int) {
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println("** Power of $n **")
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for (i in 0 until m.size) println(m[i].contentToString())
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println()
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}
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fun main(args: Array<String>) {
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val m = arrayOf(
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doubleArrayOf(3.0, 2.0),
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doubleArrayOf(2.0, 1.0)
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)
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for (i in 0..10) printMatrix(m pow i, i)
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}
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