A-M baby

Task/Matrix-multiplication/Groovy/matrix-multiplication-1.groovy

@@ -0,0 +1,17 @@
+def assertConformable = { a, b ->
+    assert a instanceof List
+    assert b instanceof List
+    assert a.every { it instanceof List && it.size() == b.size() }
+    assert b.every { it instanceof List && it.size() == b[0].size() }
+}
+
+def matmulWOIL = { a, b ->
+    assertConformable(a, b)
+
+    def bt = b.transpose()
+    a.collect { ai ->
+        bt.collect { btj ->
+            [ai, btj].transpose().collect { it[0] * it[1] }.sum()
+        }
+    }
+}

Task/Matrix-multiplication/Groovy/matrix-multiplication-2.groovy

@@ -0,0 +1,9 @@
+def matmulWOT = { a, b ->
+    assertConformable(a, b)
+
+    (0..<a.size()).collect { i ->
+        (0..<b[0].size()).collect { j ->
+            (0..<b.size()).collect { k -> a[i][k] * b[k][j] }.sum()
+        }
+    }
+}

Task/Matrix-multiplication/Groovy/matrix-multiplication-3.groovy

@@ -0,0 +1,11 @@
+def m4by2 = [ [  1,  2 ],
+              [  3,  4 ],
+              [  5,  6 ],
+              [  7,  8 ] ]
+
+def m2by3 = [ [  1,  2,  3 ],
+              [  4,  5,  6 ] ]
+
+matmulWOIL(m4by2, m2by3).each { println it }
+println()
+matmulWOT(m4by2, m2by3).each { println it }