/* nag_dgelsy (f08bac) Example Program. * * Copyright 2011 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include int main(void) { /* Scalars */ double rcond; Integer exit_status = 0, i, j, m, n, nrhs, rank, pda, pdb; /* Arrays */ double *a = 0, *b = 0; Integer *jpvt = 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_dgelsy (f08bac) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%ld%*[^\n]", &m, &n, &nrhs); /* Allocate memory */ if (!(a = NAG_ALLOC(m * n, double)) || !(b = NAG_ALLOC(m * nrhs, double)) || !(jpvt = NAG_ALLOC(n, Integer))) { printf("Allocation failure\n"); exit_status = -1; goto END; } #ifdef NAG_COLUMN_MAJOR pda = m; pdb = m; #else pda = n; pdb = nrhs; #endif /* Read A and 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_iload (f16dbc). * Initialize jpvt to be zero so that all columns are free. */ nag_iload(n, 0, jpvt, 1, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_iload (f16dbc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Choose rcond to reflect the relative accuracy of the input data */ rcond = 0.01; /* nag_dgelsy (f08bac). * Solve the least squares problem min( norm2(b - Ax) ) for the x * of minimum norm. */ nag_dgelsy(order, m, n, nrhs, a, pda, b, pdb, jpvt, rcond, &rank, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgelsy (f08bac).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print solution */ printf("Least squares solution\n"); for (i = 1; i <= n; ++i) { for (j = 1; j <= nrhs; ++j) printf("%11.4f%s", B(i,j), j%7 == 0?"\n":" "); printf("\n"); } /* Print the effective rank of A */ printf("\nTolerance used to estimate the rank of A\n"); printf("%11.2e\n", rcond); printf("Estimated rank of A\n%6ld\n", rank); END: NAG_FREE(a); NAG_FREE(b); NAG_FREE(jpvt); return exit_status; } #undef A #undef B