Kronecker product: Difference between revisions

=={{header|Swift}}==

<lang swift>func kronecker(m1: [[Int]], m2: [[Int]]) -> [[Int]] {

let m = m1.count

let n = m1[0].count

let p = m2.count

let q = m2[0].count

let rtn = m * p

let ctn = n * q

var res = Array(repeating: Array(repeating: 0, count: ctn), count: rtn)

for i in 0..<m {

for j in 0..<n {

for k in 0..<p {

for l in 0..<q {

res[p * i + k][q * j + l] = m1[i][j] * m2[k][l]

}

}

}

}

return res

}

func printMatrix<T>(_ matrix: [[T]]) {

guard !matrix.isEmpty else {

print()

return

}

let rows = matrix.count

let cols = matrix[0].count

for i in 0..<rows {

for j in 0..<cols {

print(matrix[i][j], terminator: " ")

}

print()

}

}

func printProducts(a: [[Int]], b: [[Int]]) {

print("Matrix A:")

printMatrix(a)

print("Matrix B:")

printMatrix(b)

print("kronecker a b:")

printMatrix(kronecker(m1: a, m2: b))

print()

}

let a = [

[1, 2],

[3, 4]

]

let b = [

[0, 5],

[6, 7]

]

printProducts(a: a, b: b)

let a2 = [

[0, 1, 0],

[1, 1, 1],

[0, 1, 0]

]

let b2 = [

[1, 1, 1, 1],

[1, 0, 0, 1],

[1, 1, 1, 1]

]

printProducts(a: a2, b: b2)</lang>

{{out}}

<pre>Matrix A:

1 2

3 4

Matrix B:

0 5

6 7

kronecker a b:

0 5 0 10

6 7 12 14

0 15 0 20

18 21 24 28

Matrix A:

0 1 0

1 1 1

0 1 0

Matrix B:

1 1 1 1

1 0 0 1

1 1 1 1

kronecker a b:

0 0 0 0 1 1 1 1 0 0 0 0

0 0 0 0 1 0 0 1 0 0 0 0

0 0 0 0 1 1 1 1 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1 1

1 0 0 1 1 0 0 1 1 0 0 1

1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 1 1 1 1 0 0 0 0

0 0 0 0 1 0 0 1 0 0 0 0

0 0 0 0 1 1 1 1 0 0 0 0 </pre>