// Multiply rows of A by columns of B.
type Matrix = Vector[Vector[Int]]
// Print a 2D array (matrix)
def printMatrix(arr2d: Matrix): Unit =
arr2d.foreach { row =>
row.foreach { value =>
print(f"$value%4d")
}
println()
}
// Multiply matrices A and B into C
def multipleMatrix(a: Matrix, b: Matrix): Matrix =
val rows = a.length
val cols = b.head.length
val inner = a.head.length
Vector.tabulate(rows, cols) { (i, j) =>
(0 until inner).map(k => a(i)(k) * b(k)(j)).sum
}
@main def run(): Unit =
// Create matrices
val a: Matrix = Vector(
Vector(1, 8, 5),
Vector(6, 7, 1),
Vector(8, 7, 6)
)
val b: Matrix = Vector(
Vector(4, 8, 1),
Vector(6, 5, 3),
Vector(4, 6, 5)
)
// c[0][0] = (a[0][0] * b[0][0]) + (a[0][1] * b[1][0]) + (a[0][2] * b[2][0])
printMatrix(a)
println()
printMatrix(b)
println()
val c: Matrix = multipleMatrix(a, b)
printMatrix(c)
/*
run:
1 8 5
6 7 1
8 7 6
4 8 1
6 5 3
4 6 5
72 78 50
70 89 32
98 135 59
*/
