September Morn Update

Task/Matrix-multiplication/Standard-ML/matrix-multiplication-1.ml

@@ -0,0 +1,19 @@
+structure Matrix = struct
+local
+    open Array2
+    fun dot(x,y) = Vector.foldli (fn (i,xi,agg) => agg+xi*Vector.sub(y,i)) 0 x
+in
+val fromList = fromList
+fun x*y = tabulate ColMajor (nRows x, nCols y, fn (i,j) => dot(row(x,i),column(y,j)))
+(* for display *)
+fun toList a =
+    List.tabulate(nRows a, fn i => List.tabulate(nCols a, fn j => sub(a,i,j)))
+end
+end;
+(* example *)
+let open Matrix
+    val m1 = fromList [[1,2],[3,4]]
+    val m2 = fromList [[~3,~8,3],[~2,1,4]]
+in
+    toList (m1*m2)
+end;

Task/Matrix-multiplication/Standard-ML/matrix-multiplication-2.ml

@@ -0,0 +1 @@
+val it = [[~7,~6,11],[~17,~20,25]] : int list list