Matrix Operations

class Matrix(private val rows: Int, private val cols: Int) {
    private val data: Array<DoubleArray> = Array(rows) { DoubleArray(cols) }
    
    operator fun get(row: Int, col: Int): Double = data[row][col]
    
    operator fun set(row: Int, col: Int, value: Double) {
        data[row][col] = value
    }
    
    // Matrix multiplication
    operator fun times(other: Matrix): Matrix {
        require(this.cols == other.rows) { 
            "Cannot multiply matrices: columns of first matrix must equal rows of second matrix" 
        }
        
        val result = Matrix(this.rows, other.cols)
        
        for (i in 0 until this.rows) {
            for (j in 0 until other.cols) {
                var sum = 0.0
                for (k in 0 until this.cols) {
                    sum += this[i, k] * other[k, j]
                }
                result[i, j] = sum
            }
        }
        
        return result
    }
    
    // Matrix transpose
    fun transpose(): Matrix {
        val result = Matrix(cols, rows)
        
        for (i in 0 until rows) {
            for (j in 0 until cols) {
                result[j, i] = this[i, j]
            }
        }
        
        return result
    }
    
    // Matrix addition
    operator fun plus(other: Matrix): Matrix {
        require(this.rows == other.rows && this.cols == other.cols) {
            "Matrices must have same dimensions for addition"
        }
        
        val result = Matrix(rows, cols)
        
        for (i in 0 until rows) {
            for (j in 0 until cols) {
                result[i, j] = this[i, j] + other[i, j]
            }
        }
        
        return result
    }
    
    override fun toString(): String {
        return data.joinToString("\n") { row ->
            row.joinToString(" ") { "%.2f".format(it) }
        }
    }
}

fun main() {
    // Create matrices
    val matrix1 = Matrix(2, 3).apply {
        this[0, 0] = 1.0; this[0, 1] = 2.0; this[0, 2] = 3.0
        this[1, 0] = 4.0; this[1, 1] = 5.0; this[1, 2] = 6.0
    }
    
    val matrix2 = Matrix(3, 2).apply {
        this[0, 0] = 7.0; this[0, 1] = 8.0
        this[1, 0] = 9.0; this[1, 1] = 10.0
        this[2, 0] = 11.0; this[2, 1] = 12.0
    }
    
    println("Matrix 1:")
    println(matrix1)
    println("\nMatrix 2:")
    println(matrix2)
    println("\nMatrix 1 * Matrix 2:")
    println(matrix1 * matrix2)
    println("\nMatrix 1 Transposed:")
    println(matrix1.transpose())
}