1.示例源码

#include <stdio.h>int min(int m, int n){  return m<n? m:n;}void print_matrix(double* A, int m, int n, int lda)
{for (int i = 0; i < m; i++){for (int j = 0; j < n; j++){//printf("%7.4f ", A[i + j*lda]);printf("%7.4f, ", A[i + j * lda]);}printf("; ...\n");}
}int main()
{int m = 4; // Number of rows in the matrixint n = 4; // Number of columns in the matrix//double A[] = {1.0, 4.0, 2.0, 5.0, 3.0, 6.0}; // Input matrix//double A[] = { 0.2029,  0.1386,  0.0747,  0.4070,  0.3765,  0.9046,  0.5039,  0.1746,  0.1999,  0.1830,  0.0428,  0.5782,  0.4996,  0.0351,  0.3829,  0.4178,  0.7555,  0.8836,  0.1705,  0.5099,  0.7483,  0.1933,  0.0904,  0.0653,  0.5536,  0.1145,  0.0588,  0.7315,  0.5379,  0.1212,  0.4357,  0.5835,  0.5118,  0.1740,  0.6601,  0.8425,  0.6992,  0.4402,  0.2148,  0.6044,  0.6756,  0.1013,  0.3293,  0.3598,  0.9349,  0.2801,  0.3233,  0.5857,  0.2380}; // Input matrixdouble A[] = {0.2029,  0.1386,  0.0747,  0.4070,0.3765,  0.9046,  0.5039,  0.1746,0.1999,  0.1830,  0.0428,  0.5782,0.4996,  0.0351,  0.3829,  0.4178}; // Input matrixprintf("A =\n");print_matrix(A, m, n, m);int lda = m; // Leading dimension of Adouble tau[min(m,n)]; // Array to store elementary reflectorsint info; // Output variable for error infoint lwork = -1;double* work = (double*)malloc(8);// Call the LAPACK dgeqrf function for QR decompositiondgeqrf_(&m, &n, A, &lda, tau, work, &lwork, &info);lwork = (int)work[0];printf("lwork=%d\n", lwork);work = (double*)malloc(lwork*sizeof(double)); // Workspace array// Call the LAPACK dgeqrf function again with correct workspacedgeqrf_(&m, &n, A, &lda, tau, work, &lwork, &info);if (info == 0) {printf("QR decomposition successful!\n");// Print the decomposed matrix Aprintf("Decomposed matrix A:\n");for (int i = 0; i < m; i++) {for (int j = 0; j < n; j++) {printf("%8.5f ", A[i + j*m]);}printf("\n");}} else {printf("QR decomposition failed!\n");}printf("\nTAU=\n");
for(int i=0; i<min(m,n); i++)
{printf(" %8.5f ", tau[i]);
}
printf("\n\n");return 0;
}

2. Makefile

STATIC_LIB =  ../../liblapack.a ../../librefblas.a
LD_FLAGS   =  -lgfortran  -lmEXE := dgeqrf_all: $(EXE)%: %.cgcc -g $< $(STATIC_LIB) $(LD_FLAGS) -o $@.PHONY: clean
clean:${RM} $(EXE) *.o

3. 运行