private int[,] MatrixMultipleByRecursive(MatrixWrapper matrixA, MatrixWrapper matrixB)
{
if (matrixA.ColCount != matrixB.RowCount)
{
throw new Exception($"cannot multiply two matrix. MatrixA column:{matrixA.ColCount} MatrixB Row: {matrixB.RowCount}");
}
// if any of matrix cannot be divided any more. Just use normal Algorithem to do the calculation.
if (matrixA.RowCount == 1 || matrixA.ColCount == 1 ||
matrixB.RowCount == 1 || matrixB.ColCount == 1)
{
MatrixMultiplyNormal normalAlgorithem = new MatrixMultiplyNormal();
return(normalAlgorithem.Multiply(matrixA, matrixB));
}
int[,] resultRawMatrix = new int[matrixA.RowCount, matrixB.ColCount];
MatrixDivideResult dividedMatrixA = new MatrixDivideResult(matrixA);
MatrixDivideResult dividedMatrixB = new MatrixDivideResult(matrixB);
// 11
this.CopyTo(MatrixAdd(MatrixMultipleByRecursive(dividedMatrixA.A11, dividedMatrixB.A11), MatrixMultipleByRecursive(dividedMatrixA.A12, dividedMatrixB.A21))
, new MatrixWrapper(resultRawMatrix, 0, dividedMatrixA.A11.RowCount - 1, 0, dividedMatrixA.A11.ColCount - 1));
// 12
this.CopyTo(MatrixAdd(MatrixMultipleByRecursive(dividedMatrixA.A11, dividedMatrixB.A12), MatrixMultipleByRecursive(dividedMatrixA.A12, dividedMatrixB.A22))
, new MatrixWrapper(resultRawMatrix, 0, dividedMatrixA.A11.RowCount - 1, dividedMatrixA.A11.ColCount, dividedMatrixA.A11.ColCount + dividedMatrixA.A12.ColCount - 1));
// 21
this.CopyTo(MatrixAdd(MatrixMultipleByRecursive(dividedMatrixA.A21, dividedMatrixB.A11), MatrixMultipleByRecursive(dividedMatrixA.A22, dividedMatrixB.A21))
, new MatrixWrapper(resultRawMatrix, dividedMatrixA.A11.RowCount, dividedMatrixA.A11.RowCount + dividedMatrixA.A21.RowCount - 1, 0, dividedMatrixA.A11.ColCount - 1));
// 22
this.CopyTo(MatrixAdd(MatrixMultipleByRecursive(dividedMatrixA.A21, dividedMatrixB.A12), MatrixMultipleByRecursive(dividedMatrixA.A22, dividedMatrixB.A22))
, new MatrixWrapper(resultRawMatrix, dividedMatrixA.A11.RowCount, dividedMatrixA.A11.RowCount + dividedMatrixA.A21.RowCount - 1, dividedMatrixA.A11.ColCount, dividedMatrixA.A11.ColCount + dividedMatrixA.A12.ColCount - 1));
return(resultRawMatrix);
}
private int[,] MultiplyByStrassen(MatrixWrapper matrixA, MatrixWrapper matrixB)
{
// if any of matrix cannot be divided any more. Just use normal Algorithem to do the calculation.
if (matrixA.RowCount == 1 || matrixA.ColCount == 1 ||
matrixB.RowCount == 1 || matrixB.ColCount == 1)
{
MatrixMultiplyNormal normalAlgorithem = new MatrixMultiplyNormal();
return(normalAlgorithem.Multiply(matrixA, matrixB));
}
// Step 1 Divide matrix.
MatrixDivideResult matrixDividedA = new MatrixDivideResult(matrixA);
MatrixDivideResult matrixDividedB = new MatrixDivideResult(matrixB);
// step 2 create the 10 S matrixs.
int[,] S1 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S2 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S3 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S4 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S5 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S6 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S7 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S8 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S9 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
int[,] S10 = new int[matrixDividedA.A11.RowCount, matrixDividedA.A11.ColCount];
S1 = MatrixSubtract(matrixDividedB.A12.ToRawMatrix(), matrixDividedB.A22.ToRawMatrix());
S2 = MatrixAdd(matrixDividedA.A11.ToRawMatrix(), matrixDividedA.A12.ToRawMatrix());
S3 = MatrixAdd(matrixDividedA.A21.ToRawMatrix(), matrixDividedA.A22.ToRawMatrix());
S4 = MatrixSubtract(matrixDividedB.A21.ToRawMatrix(), matrixDividedB.A11.ToRawMatrix());
S5 = MatrixAdd(matrixDividedA.A11.ToRawMatrix(), matrixDividedA.A22.ToRawMatrix());
S6 = MatrixAdd(matrixDividedB.A11.ToRawMatrix(), matrixDividedB.A22.ToRawMatrix());
S7 = MatrixSubtract(matrixDividedA.A12.ToRawMatrix(), matrixDividedA.A22.ToRawMatrix());
S8 = MatrixAdd(matrixDividedB.A21.ToRawMatrix(), matrixDividedB.A22.ToRawMatrix());
S9 = MatrixSubtract(matrixDividedA.A11.ToRawMatrix(), matrixDividedA.A21.ToRawMatrix());
S10 = MatrixAdd(matrixDividedB.A11.ToRawMatrix(), matrixDividedB.A12.ToRawMatrix());
// step3 call multiply Recursive.
int[,] P1 = MultiplyByStrassen(matrixDividedA.A11, new MatrixWrapper(S1));
int[,] P2 = MultiplyByStrassen(new MatrixWrapper(S2), matrixDividedB.A22);
int[,] P3 = MultiplyByStrassen(new MatrixWrapper(S3), matrixDividedB.A11);
int[,] P4 = MultiplyByStrassen(matrixDividedA.A22, new MatrixWrapper(S4));
int[,] P5 = MultiplyByStrassen(new MatrixWrapper(S5), new MatrixWrapper(S6));
int[,] P6 = MultiplyByStrassen(new MatrixWrapper(S7), new MatrixWrapper(S8));
int[,] P7 = MultiplyByStrassen(new MatrixWrapper(S9), new MatrixWrapper(S10));
// step4 matrix add
int[,] C11 = MatrixListAdd(new List <int[, ]>()
{
P5, P4, MatrixMultiplyConst(P2, -1), P6
});
int[,] C12 = MatrixAdd(P1, P2);
int[,] C21 = MatrixAdd(P3, P4);
int[,] C22 = MatrixListAdd(new List <int[, ]>()
{
P5, P1, MatrixMultiplyConst(P3, -1), MatrixMultiplyConst(P7, -1)
});
int[,] resultRawMatrix = new int[matrixA.RowCount, matrixB.ColCount];
// step5 merge all the partial matrix to a whole
// 11
this.CopyTo(C11, new MatrixWrapper(resultRawMatrix, 0, matrixDividedA.A11.RowCount - 1, 0, matrixDividedA.A11.ColCount - 1));
// 12
this.CopyTo(C12, new MatrixWrapper(resultRawMatrix, 0, matrixDividedA.A11.RowCount - 1, matrixDividedA.A11.ColCount, matrixDividedA.A11.ColCount + matrixDividedA.A12.ColCount - 1));
// 21
this.CopyTo(C21, new MatrixWrapper(resultRawMatrix, matrixDividedA.A11.RowCount, matrixDividedA.A11.RowCount + matrixDividedA.A21.RowCount - 1, 0, matrixDividedA.A11.ColCount - 1));
// 22
this.CopyTo(C22, new MatrixWrapper(resultRawMatrix, matrixDividedA.A11.RowCount, matrixDividedA.A11.RowCount + matrixDividedA.A21.RowCount - 1, matrixDividedA.A11.ColCount, matrixDividedA.A11.ColCount + matrixDividedA.A12.ColCount - 1));
return(resultRawMatrix);
}