update

2025.07.24_programming_with_python_and_fortran/example_3/a.py

@@ -0,0 +1,31 @@
+import numpy as np
+import example
+
+A = [[1.0, 2.0, 3.0],
+    [0.0, 1.0, 4.0],
+    [5.0, 6.0, 0.0]]
+
+Ainv_1 = np.asfortranarray(np.empty_like(A))
+example.inverse_matrix(A, Ainv_1) # 调用 Fortran 子程序
+print(Ainv_1)
+
+Ainv_2 = np.linalg.inv(A)
+print(Ainv_2)
+
+print('---')
+
+# 时间对比
+
+A = np.random.rand(3000, 3000)
+
+import time
+start = time.time()
+Ainv_1 = np.asfortranarray(np.empty_like(A))
+example.inverse_matrix(A, Ainv_1) # 调用 Fortran 子程序
+end = time.time()
+print('Python + Fortran 求逆时间：', end - start)
+
+start = time.time()
+Ainv_2 = np.linalg.inv(A)
+end = time.time()
+print('Python np.linalg.inv() 求逆时间：', end - start)

2025.07.24_programming_with_python_and_fortran/example_3/example.f90

@@ -0,0 +1,19 @@
+! 矩阵求逆子程序
+subroutine inverse_matrix(A, Ainv)
+    implicit none
+    real(8), intent(in) :: A(:,:)       ! 输入矩阵
+    real(8), intent(inout) :: Ainv(:,:)    ! 输出逆矩阵
+    real(8), allocatable :: work(:)
+    integer, allocatable :: ipiv(:)
+    integer :: n, info
+
+    n = size(A,1)
+    allocate(ipiv(n), work(n))
+    
+    Ainv = A  ! 复制输入矩阵
+    
+    call dgetrf(n, n, Ainv, n, ipiv, info)  ! LU 分解
+    call dgetri(n, Ainv, n, ipiv, work, n, info) ! 计算逆矩阵
+        
+    deallocate(ipiv, work)
+end subroutine inverse_matrix