Kronecker product: Difference between revisions

</pre>

=={{header|SuperCollider}}==

<lang SuperCollider>// the iterative version is derived from the javascript one here:

(

f = { |a, b|

var m = a.size;

var n = a[0].size;

var p = b.size;

var q = b[0].size;

var rtn = m * p;

var ctn = n * q;

var res = { 0.dup(ctn) }.dup(rtn);

m.do { |i|

n.do { |j|

p.do { |k|

q.do { |l|

res[p*i+k][q*j+l] = a[i][j] * b[k][l];

}

}

}

};

res

};

)

// Like APL/J, SuperCollider has applicative operators, so here is a shorter version.

// the idea is to first replace every element of b with its product with all of a

// and then reshape the matrix appropriately

// note that +++ is lamination: [[1, 2, 3], [4, 5, 6]] +++ [100, 200] returns [ [ 1, 2, 3, 100 ], [ 4, 5, 6, 200 ] ].

(

f = { |a, b|

a.collect { |x|

x.collect { |y| b * y }.reduce('+++')

}.reduce('++')

}

)

// to apply either of the two functions:

(

x = f.(

[

[0, 1, 0],

[1, 1, 1],

[0, 1, 0]

],

[

[1, 1, 1, 1],

[1, 0, 0, 1],

[1, 1, 1, 1]

]

)

)

</lang>

Results in:

<pre>

[

[ 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 ]

]