Fortran向量和矩陣乘法函式

下表描述了向量和矩陣乘法函式：

函式	描述
dot_product(vector_a, vector_b)	函式返回兩個輸入向量，它必須具有相同長度的標量積。
matmul (matrix_a, matrix_b)	它返回兩個矩陣的矩陣乘積，它必須是一致的，即具有相似大小 (m, k) 和 (k, n)

範例

下面的例子演示了內積：

program arrayDotProduct

   real, dimension(5) :: a, b
   integer:: i, asize, bsize
   
   asize = size(a)
   bsize = size(b)
   
   do i = 1, asize
      a(i) = i
   end do
   
   do i = 1, bsize
      b(i) = i*2
   end do
   
   do i = 1, asize
      Print *, a(i)
   end do
   
   do i = 1, bsize
      Print *, b(i)
   end do
   
   Print*, 'Vector Multiplication: Dot Product:'
   Print*, dot_product(a, b)
   
end program arrayDotProduct

當上述程式碼被編譯和執行時，它產生了以下結果：

1.00000000    
2.00000000    
3.00000000    
4.00000000    
5.00000000    
2.00000000    
4.00000000    
6.00000000    
8.00000000    
10.0000000    
Vector Multiplication: Dot Product:
110.000000

範例

下面的例子演示了矩陣乘法：

program matMulProduct

   integer, dimension(3,3) :: a, b, c
   integer :: i, j
    
   do i = 1, 3
      do j = 1, 3
         a(i, j) = i+j
      end do
   end do
   
   print *, 'Matrix Multiplication: A Matrix'
   
   do i = 1, 3
      do j = 1, 3
         print*, a(i, j)
      end do
   end do
   
   do i = 1, 3
      do j = 1, 3
         b(i, j) = i*j
      end do
   end do
   
   Print*, 'Matrix Multiplication: B Matrix'
   
   do i = 1, 3
      do j = 1, 3
         print*, b(i, j)
      end do
   end do
   
   c = matmul(a, b)
   Print*, 'Matrix Multiplication: Result Matrix'
   
   do i = 1, 3
      do j = 1, 3
         print*, c(i, j)
      end do
   end do
   
end program matMulProduct

當上述程式碼被編譯和執行時，它產生了以下結果：

Matrix Multiplication: A Matrix
2
3
4
3
4
5
4
5
6
 Matrix Multiplication: B Matrix
1
2
3
2
4
6
3
6
9
Matrix Multiplication: Result Matrix
20
40
60
26
52
78
32
64
96