Data update

Task/Matrix-multiplication/Delphi/matrix-multiplication.pas

@@ -0,0 +1,93 @@
+program Matrix_multiplication;
+
+{$APPTYPE CONSOLE}
+
+uses
+  System.SysUtils;
+
+type
+  TMatrix = record
+    values: array of array of Double;
+    Rows, Cols: Integer;
+    constructor Create(Rows, Cols: Integer);
+    class operator Multiply(a: TMatrix; b: TMatrix): TMatrix;
+    function ToString: string;
+  end;
+
+{ TMatrix }
+
+constructor TMatrix.Create(Rows, Cols: Integer);
+var
+  i: Integer;
+begin
+  Self.Rows := Rows;
+  self.Cols := Cols;
+  SetLength(values, Rows);
+  for i := 0 to High(values) do
+    SetLength(values[i], Cols);
+end;
+
+class operator TMatrix.Multiply(a, b: TMatrix): TMatrix;
+var
+  rows, cols, l: Integer;
+  i, j: Integer;
+  sum: Double;
+  k: Integer;
+begin
+  rows := a.Rows;
+  cols := b.Cols;
+  l := a.Cols;
+  if l <> b.Rows then
+    raise Exception.Create('Illegal matrix dimensions for multiplication');
+  result := TMatrix.create(a.rows, b.Cols);
+  for i := 0 to rows - 1 do
+    for j := 0 to cols - 1 do
+    begin
+      sum := 0.0;
+      for k := 0 to l - 1 do
+        sum := sum + (a.values[i, k] * b.values[k, j]);
+      result.values[i, j] := sum;
+    end;
+end;
+
+function TMatrix.ToString: string;
+var
+  i, j: Integer;
+begin
+  Result := '[';
+  for i := 0 to 2 do
+  begin
+    if i > 0 then
+      Result := Result + #10;
+    Result := Result + '[';
+    for j := 0 to 2 do
+    begin
+      if j > 0 then
+        Result := Result + ', ';
+      Result := Result + format('%5.2f', [values[i, j]]);
+    end;
+    Result := Result + ']';
+  end;
+  Result := Result + ']';
+end;
+
+var
+  a, b, r: TMatrix;
+  i, j: Integer;
+
+begin
+  a := TMatrix.Create(3, 3);
+  b := TMatrix.Create(3, 3);
+  a.values := [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
+  b.values := [[2, 2, 2], [5, 5, 5], [7, 7, 7]];
+  r := a * b;
+
+  Writeln('a: ');
+  Writeln(a.ToString, #10);
+  Writeln('b: ');
+  Writeln(b.ToString, #10);
+  Writeln('a * b:');
+  Writeln(r.ToString);
+  readln;
+
+end.