/* nag_dgbsv (f07bac) Example Program. * * Copyright 2008 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer exit_status = 0, i, j, kl, ku, n, nrhs, pdab, pdb; /* Arrays */ double *ab = 0, *b = 0; Integer *ipiv = 0; /* Nag Types */ NagError fail; Nag_OrderType order; #ifdef NAG_COLUMN_MAJOR #define AB(I, J) ab[(J-1)*pdab + kl + ku + I - J] #define B(I, J) b[(J-1)*pdb + I - 1] order = Nag_ColMajor; #else #define AB(I, J) ab[(I-1)*pdab + kl + J - I] #define B(I, J) b[(I-1)*pdb + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dgbsv (f07bac) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%ld%*[^\n] ", &n, &kl, &ku); scanf("%ld%*[^\n] ", &nrhs); if (n < 0 || kl < 0 || ku < 0 || nrhs < 0) { printf("One or more of n, kl, ku or nrhs has illegal value\n"); exit_status = 1; goto END; } pdab = 2*kl+ku+1; #ifdef NAG_COLUMN_MAJOR pdb = n; #else pdb = nrhs; #endif /* Allocate memory */ if (!(ab = NAG_ALLOC((2*kl+ku+1)*n, double)) || !(b = NAG_ALLOC(n*nrhs, double)) || !(ipiv = NAG_ALLOC(n, Integer))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the band matrix A and the right hand side b from data file */ for (i = 1; i <= n; ++i) for (j = MAX(i - kl, 1); j <= MIN(i + ku, n); ++j) scanf("%lf", &AB(i, j)); scanf("%*[^\n] "); for (i = 1; i <= n; ++i) for (j = 1; j <= nrhs; ++j) scanf("%lf", &B(i, j)); scanf("%*[^\n] "); /* Solve the equations Ax = b for x using nag_dgbsv (f07bac). */ nag_dgbsv(order, n, kl, ku, nrhs, ab, pdab, ipiv, b, pdb, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgbsv (f07bac).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print solution */ printf("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 details of the factorization */ printf("\n"); fflush(stdout); nag_band_real_mat_print(order, n, n, kl, kl+ku, ab, pdab, "Details of factorization", 0, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_band_real_mat_print (x04cec).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print pivot indices' */ printf("\nPivot indices\n"); for (i = 1; i <= n; ++i) printf("%11ld%s", ipiv[i-1], i%7 == 0?"\n":" "); printf("\n"); END: if (ab) NAG_FREE(ab); if (b) NAG_FREE(b); if (ipiv) NAG_FREE(ipiv); return exit_status; } #undef AB #undef B