update

2025.09.28_cpp_openblas_test/openblas_test.cpp

@@ -0,0 +1,58 @@
+#include <iostream>
+#include <vector>
+#include <cmath>
+
+extern "C" {
+    void dgetrf_(int* m, int* n, double* a, int* lda, int* ipiv, int* info);
+    void dgetri_(int* n, double* a, int* lda, int* ipiv, double* work, int* lwork, int* info);
+}
+
+int main() {
+    const int N = 3;
+    
+    double A_data[] = {
+        1, 0, 5,   // 第1列
+        2, 1, 6,   // 第2列
+        3, 4, 0    // 第3列
+    };
+    std::vector<double> A(A_data, A_data + 9);
+
+    std::cout << "Original matrix (column-major):\n";
+    for (int i = 0; i < N; ++i) {
+        for (int j = 0; j < N; ++j) {
+            std::cout << A[j*N + i] << " ";
+        }
+        std::cout << "\n";
+    }
+
+    // LU 分解
+    std::vector<int> ipiv(N);
+    int info;
+    int n = N;
+    int lda = N;
+    
+    dgetrf_(&n, &n, &A[0], &lda, &ipiv[0], &info);
+    if (info != 0) {
+        std::cerr << "LU decomposition failed! (info=" << info << ")\n";
+        return 1;
+    }
+
+    // 计算逆矩阵
+    std::vector<double> work(N);
+    int lwork = N; // 关键：必须是可变变量
+    dgetri_(&n, &A[0], &lda, &ipiv[0], &work[0], &lwork, &info);
+    if (info != 0) {
+        std::cerr << "Matrix inversion failed! (info=" << info << ")\n";
+        return 1;
+    }
+
+    std::cout << "\nInverse matrix:\n";
+    for (int i = 0; i < N; ++i) {
+        for (int j = 0; j < N; ++j) {
+            std::cout << A[j*N + i] << " ";
+        }
+        std::cout << "\n";
+    }
+
+    return 0;
+}

2025.09.28_cpp_openblas_test/openblas_test_wtih_eigen.cpp

@@ -0,0 +1,19 @@
+#define EIGEN_USE_BLAS
+#include <iostream>
+#include "Eigen/Dense" // #include <Eigen/Dense>
+
+int main() {
+    Eigen::MatrixXd A(4, 4);
+    A << 2, 1, 1, 0,
+         1, 3, 1, 1,
+         1, 1, 4, 1,
+         0, 1, 1, 5;
+
+    Eigen::MatrixXd A_inv = A.inverse();
+
+    std::cout << "A:\n" << A << std::endl;
+    std::cout << "\nA_inv:\n" << A_inv << std::endl;
+    std::cout << "\nA*A_inv:\n" << A * A_inv << std::endl;
+
+    return 0;
+}

2025.09.28_fortran_openblas_test/openblas_test.f90

@@ -0,0 +1,25 @@
+program invert_simple
+    implicit none
+    integer, parameter :: n = 2
+    double precision :: a(n,n)
+    integer :: ipiv(n)
+    double precision :: work(n)  ! 最小工作空间（LWORK = N）
+    integer :: info
+
+    ! 初始化一个简单的可逆矩阵: [[2, 1], [1, 2]]
+    a(1,1) = 2.0d0; a(1,2) = 1.0d0
+    a(2,1) = 1.0d0; a(2,2) = 2.0d0
+
+    ! LU 分解
+    call DGETRF(n, n, a, n, ipiv, info)
+    if (info /= 0) stop 'DGETRF failed'
+
+    ! 求逆（使用最小工作空间 LWORK = N）
+    call DGETRI(n, a, n, ipiv, work, n, info)
+    if (info /= 0) stop 'DGETRI failed'
+
+    ! 输出结果（应为 [[0.6667, -0.3333], [-0.3333, 0.6667]]）
+    print *, 'Inverse:'
+    print *, a(1,1), a(1,2)
+    print *, a(2,1), a(2,2)
+end program