/* nag_dgerqf (f08chc) Example Program. * * Copyright 2011 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, m, n, nrhs, pda, pdb, pdx; Integer exit_status = 0; /* Arrays */ double *a = 0, *b = 0, *tau = 0, *x = 0; /* Nag Types */ Nag_OrderType order; NagError fail; #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); printf("nag_dgerqf (f08chc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%ld%*[^\n]", &m, &n, &nrhs); #ifdef NAG_COLUMN_MAJOR pda = m; pdb = m; pdx = n; #else pda = n; pdb = nrhs; pdx = 1; #endif /* Allocate memory */ if (!(a = NAG_ALLOC(m*n, double)) || !(b = NAG_ALLOC(m*nrhs, double)) || !(tau = NAG_ALLOC(MAX(1, MIN(m, n)), double)) || !(x = NAG_ALLOC(n, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the matrix A and the vectors b from data file */ for (i = 1; i <= m; ++i) for (j = 1; j <= n; ++j) scanf("%lf", &A(i, j)); scanf("%*[^\n]"); for (i = 1; i <= m; ++i) for (j = 1; j <= nrhs; ++j) scanf("%lf", &B(i, j)); scanf("%*[^\n]"); /* nag_dgerqf (f08chc). * Compute the RQ factorization of A. */ nag_dgerqf(order, m, n, a, pda, tau, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgerqf (f08chc).\n%s\n", fail.message); exit_status = 1; goto END; } /* nag_dge_copy (f16qfc). * Copy the m element vector b into x2, where x2 is the vector * containing the elements x(n-m+1), ..., x(n) of x. */ nag_dge_copy(order, Nag_NoTrans, m, 1, &B(1, 1), pdb, &x[n - m], pdx, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dge_copy (f16qfc).\n%s\n", fail.message); exit_status = 1; goto END; } /* nag_dtrtrs (f07tec). * Solve R*y2 = b, storing the result in x2. */ nag_dtrtrs(order, Nag_Upper, Nag_NoTrans, Nag_NonUnitDiag, m, 1, &A(1, n - m + 1), pda, &x[n - m], pdx, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dtrtrs (f07tec).\n%s\n", fail.message); exit_status = 1; goto END; } /* nag_dload (f16fbc). * Set y1 to zero (stored in rows 1 to (n-m) of x). */ nag_dload(n - m, 0.0, x, 1, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dload (f16fbc).\n%s\n", fail.message); exit_status = 1; goto END; } /* nag_dormrq (f08ckc). * Compute the minimum-norm solution x = (Q**T)*y. */ nag_dormrq(order, Nag_LeftSide, Nag_Trans, n, 1, m, a, pda, tau, x, pdx, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dormrq (f08ckc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print minimum-norm solution */ printf("Minimum-norm solution\n"); for (i = 0; i < n; ++i) printf("%9.4f%s", x[i], (i+1)%8 == 0?"\n":" "); END: NAG_FREE(a); NAG_FREE(b); NAG_FREE(tau); NAG_FREE(x); return exit_status; } #undef A #undef B