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