/* nag_dgetri (f07ajc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. * Mark 7b revised, 2004. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, n, pda; Integer exit_status=0; NagError fail; Nag_OrderType order; /* Arrays */ double *a=0; Integer *ipiv=0; #ifdef NAG_COLUMN_MAJOR #define A(I,J) a[(J-1)*pda + I - 1] order = Nag_ColMajor; #else #define A(I,J) a[(I-1)*pda + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); Vprintf("nag_dgetri (f07ajc) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%*[^\n] ", &n); #ifdef NAG_COLUMN_MAJOR pda = n; #else pda = n; #endif /* Allocate memory */ if ( !(a = NAG_ALLOC(n * n, double)) || !(ipiv = NAG_ALLOC(n, Integer)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A from data file */ for (i = 1; i <= n; ++i) { for (j = 1; j <= n; ++j) Vscanf("%lf", &A(i,j)); } Vscanf("%*[^\n] "); /* Factorize A */ /* nag_dgetrf (f07adc). * LU factorization of real m by n matrix */ nag_dgetrf(order, n, n, a, pda, ipiv, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dgetrf (f07adc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute inverse of A */ /* nag_dgetri (f07ajc). * Inverse of real matrix, matrix already factorized by * nag_dgetrf (f07adc) */ nag_dgetri(order, n, a, pda, ipiv, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dgetri (f07ajc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print inverse */ /* nag_gen_real_mat_print (x04cac). * Print real general matrix (easy-to-use) */ nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, a, pda, "Inverse", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } END: if (a) NAG_FREE(a); if (ipiv) NAG_FREE(ipiv); return exit_status; }