# Fortran向量和矩陣乘法函式

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)

```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```

```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   ```

```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```

```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```