/* nag_dgeqrf (f08aec) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, m, n, nrhs, pda, pdb, tau_len; Integer exit_status=0; NagError fail; Nag_OrderType order; /* Arrays */ double *a=0, *b=0, *tau=0; #ifdef NAG_COLUMN_MAJOR #define A(I,J) a[(J-1)*pda + I - 1] #define B(I,J) b[(J-1)*pdb + I - 1] order = Nag_ColMajor; #else #define A(I,J) a[(I-1)*pda + J - 1] #define B(I,J) b[(I-1)*pdb + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); Vprintf("nag_dgeqrf (f08aec) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%ld%ld%*[^\n] ", &m, &n, &nrhs); #ifdef NAG_COLUMN_MAJOR pda = m; pdb = m; #else pda = n; pdb = nrhs; #endif tau_len = MIN(m,n); /* Allocate memory */ if ( !(a = NAG_ALLOC(m * n, double)) || !(b = NAG_ALLOC(m * nrhs, double)) || !(tau = NAG_ALLOC(tau_len, double)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A and B from data file */ for (i = 1; i <= m; ++i) { for (j = 1; j <= n; ++j) Vscanf("%lf", &A(i,j)); } Vscanf("%*[^\n] "); for (i = 1; i <= m; ++i) { for (j = 1; j <= nrhs; ++j) Vscanf("%lf", &B(i,j)); } Vscanf("%*[^\n] "); /* Compute the QR factorization of A */ /* nag_dgeqrf (f08aec). * QR factorization of real general rectangular matrix */ nag_dgeqrf(order, m, n, a, pda, tau, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dgeqrf (f08aec).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute C = (Q**T)*B, storing the result in B */ /* nag_dormqr (f08agc). * Apply orthogonal transformation determined by nag_dgeqrf * (f08aec) or nag_dgeqpf (f08bec) */ nag_dormqr(order, Nag_LeftSide, Nag_Trans, m, nrhs, n, a, pda, tau, b, pdb, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dormqr (f08agc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute least-squares solution by backsubstitution in R*X = C */ /* nag_dtrtrs (f07tec). * Solution of real triangular system of linear equations, * multiple right-hand sides */ nag_dtrtrs(order, Nag_Upper, Nag_NoTrans, Nag_NonUnitDiag, n, nrhs, a, pda, b, pdb, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dtrtrs (f07tec).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print least-squares solution(s) */ /* nag_gen_real_mat_print (x04cac). * Print real general matrix (easy-to-use) */ nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, b, pdb, "Least-squares solution(s)", 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 (b) NAG_FREE(b); if (tau) NAG_FREE(tau); return exit_status; }