/* nag_dgbequ (f07bfc) Example Program. * * Copyright 2011 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include #include int main(void) { /* Scalars */ double amax, big, colcnd, rowcnd, small; Integer exit_status = 0, i, j, kl, ku, n, pdab; /* Arrays */ double *ab = 0, *c = 0, *r = 0; /* Nag Types */ NagError fail; Nag_OrderType order; Nag_Boolean scaled = Nag_FALSE; #ifdef NAG_COLUMN_MAJOR #define AB(I, J) ab[(J-1)*pdab + ku + I - J] order = Nag_ColMajor; #else #define AB(I, J) ab[(I-1)*pdab + kl + J - I] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dgbequ (f07bfc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%ld%*[^\n] ", &n, &kl, &ku); if (n < 0 || kl < 0 || ku < 0) { printf("Invalid n or kl or ku\n"); exit_status = 1; goto END; } /* Allocate arrays */ pdab = kl+ku+1; if (!(ab = NAG_ALLOC(pdab * n, double)) || !(c = NAG_ALLOC(n, double)) || !(r = NAG_ALLOC(n, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the band matrix A 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]"); /* Print the matrix A using nag_band_real_mat_print (x04cec). */ fflush(stdout); nag_band_real_mat_print(order, n, n, kl, ku, ab, pdab, "Matrix A", 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; } printf("\n"); /* Compute row and column scaling factors using nag_dgbequ (f07bfc). */ nag_dgbequ(order, n, n, kl, ku, ab, pdab, r, c, &rowcnd, &colcnd, &amax, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgbequ (f07bfc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print rowcnd, colcnd, amax and the scale factors */ printf("rowcnd = %10.1e, colcnd = %10.1e, amax = %10.1e\n\n", rowcnd, colcnd, amax); printf("Row scale factors\n"); for (i = 1; i <= n; ++i) printf("%11.1e%s", r[i-1], i%7 == 0?"\n":" "); printf("\n\nColumn scale factors\n"); for (i = 1; i <= n; ++i) printf("%11.1e%s", c[i-1], i%7 == 0?"\n":" "); /* Compute values close to underflow and overflow using * nag_real_safe_small_number (x02amc), nag_machine_precision (x02ajc) and * nag_real_base (x02bhc) */ small = nag_real_safe_small_number / nag_machine_precision * nag_real_base; big = 1.0 / small; if (colcnd < 0.1) { scaled = Nag_TRUE; /* column scale A */ for (j = 1; j <= n; ++j) for (i = MAX(1, j - ku); i <= MIN(n, j + kl); ++i) AB(i, j) *= c[j - 1]; } if (rowcnd < 0.1 || amax < small || amax > big) { /* row scale A */ scaled = Nag_TRUE; for (j = 1; j <= n; ++j) for (i = MAX(1, j - ku); i <= MIN(n, j + kl); ++i) AB(i, j) *= r[i-1]; } if (scaled) { /* Print the row and column scaled matrix using * nag_band_real_mat_print (x04cec). */ fflush(stdout); printf("\n\n"); nag_band_real_mat_print(order, n, n, kl, ku, ab, pdab, "Scaled matrix", 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; } } END: if (ab) NAG_FREE(ab); if (c) NAG_FREE(c); if (r) NAG_FREE(r); return exit_status; }