private static void StrassenMultiplyRun(Matrix A, Matrix B, Matrix C, int l, Matrix[,] f) // A * B into C, level of recursion, matrix field
{
int size = A.rows;
int h = size / 2;
if (size < 32)
{
for (int i = 0; i < C.rows; i++)
for (int j = 0; j < C.cols; j++)
{
C[i, j] = 0;
for (int k = 0; k < A.cols; k++) C[i, j] += A[i, k] * B[k, j];
}
return;
}
AplusBintoC(A, 0, 0, A, h, h, f[l, 0], h);
AplusBintoC(B, 0, 0, B, h, h, f[l, 1], h);
StrassenMultiplyRun(f[l, 0], f[l, 1], f[l, 1 + 1], l + 1, f); // (A11 + A22) * (B11 + B22);
AplusBintoC(A, 0, h, A, h, h, f[l, 0], h);
ACopytoC(B, 0, 0, f[l, 1], h);
StrassenMultiplyRun(f[l, 0], f[l, 1], f[l, 1 + 2], l + 1, f); // (A21 + A22) * B11;
ACopytoC(A, 0, 0, f[l, 0], h);
AminusBintoC(B, h, 0, B, h, h, f[l, 1], h);
StrassenMultiplyRun(f[l, 0], f[l, 1], f[l, 1 + 3], l + 1, f); //A11 * (B12 - B22);
ACopytoC(A, h, h, f[l, 0], h);
AminusBintoC(B, 0, h, B, 0, 0, f[l, 1], h);
StrassenMultiplyRun(f[l, 0], f[l, 1], f[l, 1 + 4], l + 1, f); //A22 * (B21 - B11);
AplusBintoC(A, 0, 0, A, h, 0, f[l, 0], h);
ACopytoC(B, h, h, f[l, 1], h);
StrassenMultiplyRun(f[l, 0], f[l, 1], f[l, 1 + 5], l + 1, f); //(A11 + A12) * B22;
AminusBintoC(A, 0, h, A, 0, 0, f[l, 0], h);
AplusBintoC(B, 0, 0, B, h, 0, f[l, 1], h);
StrassenMultiplyRun(f[l, 0], f[l, 1], f[l, 1 + 6], l + 1, f); //(A21 - A11) * (B11 + B12);
AminusBintoC(A, h, 0, A, h, h, f[l, 0], h);
AplusBintoC(B, 0, h, B, h, h, f[l, 1], h);
StrassenMultiplyRun(f[l, 0], f[l, 1], f[l, 1 + 7], l + 1, f); // (A12 - A22) * (B21 + B22);
/// C11
for (int i = 0; i < h; i++) // rows
for (int j = 0; j < h; j++) // cols
C[i, j] = f[l, 1 + 1][i, j] + f[l, 1 + 4][i, j] - f[l, 1 + 5][i, j] + f[l, 1 + 7][i, j];
/// C12
for (int i = 0; i < h; i++) // rows
for (int j = h; j < size; j++) // cols
C[i, j] = f[l, 1 + 3][i, j - h] + f[l, 1 + 5][i, j - h];
/// C21
for (int i = h; i < size; i++) // rows
for (int j = 0; j < h; j++) // cols
C[i, j] = f[l, 1 + 2][i - h, j] + f[l, 1 + 4][i - h, j];
/// C22
for (int i = h; i < size; i++) // rows
for (int j = h; j < size; j++) // cols
C[i, j] = f[l, 1 + 1][i - h, j - h] - f[l, 1 + 2][i - h, j - h] + f[l, 1 + 3][i - h, j - h] + f[l, 1 + 6][i - h, j - h];
}
