/* nag_dpbequ (f07hfc) Example Program. * * Copyright 2004 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include #include int main(void) { /* Scalars */ double amax, big, scond, small; Integer exit_status = 0, i, j, kd, kd1, kd2, n, pdab; /* Arrays */ double *ab = 0, *s = 0; char nag_enum_arg[40]; /* Nag Types */ NagError fail; Nag_UploType uplo; Nag_OrderType order; #ifdef NAG_COLUMN_MAJOR #define AB_UPPER(I, J) ab[(J-1)*pdab + kd + I - J] #define AB_LOWER(I, J) ab[(J-1)*pdab + I - J] order = Nag_ColMajor; #else #define AB_UPPER(I, J) ab[(I-1)*pdab + J - I] #define AB_LOWER(I, J) ab[(I-1)*pdab + kd + J - I] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dpbequ (f07hfc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%ld%*[^\n]", &n, &kd); if (n < 0 || kd < 0) { printf("Invalid n or kd\n"); exit_status = 1; goto END; } scanf(" %s%*[^\n]", nag_enum_arg); /* nag_enum_name_to_value(x04nac). * Converts NAG enum member name to value */ uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg); pdab = kd+1; /* Allocate memory */ if (!(ab = NAG_ALLOC((kd+1) * n, double)) || !(s = NAG_ALLOC(n, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the upper or lower triangular part of the band matrix A * from data file. */ if (uplo == Nag_Upper) { kd1 = 0; kd2 = kd; for (i = 1; i <= n; ++i) for (j = i; j <= MIN(n, i + kd); ++j) scanf("%lf", &AB_UPPER(i, j)); } else { kd1 = kd; kd2 = 0; for (i = 1; i <= n; ++i) for (j = MAX(1, i - kd); j <= i; ++j) scanf("%lf", &AB_LOWER(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, kd1, kd2, 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 = 2; goto END; } printf("\n"); /* Compute diagonal scaling factors using nag_dpbequ (f07hfc). */ nag_dpbequ(order, uplo, n, kd, ab, pdab, s, &scond, &amax, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dpbequ (f07hfc).\n%s\n", fail.message); exit_status = 3; goto END; } /* Print scond, amax and the scale factors */ printf("scond = %10.1e, amax = %10.1e\n", scond, amax); printf("\nDiagonal scaling factors\n"); for (i = 0; i < n; ++i) printf("%11.1e%s", s[i], i%7 == 6?"\n":" "); printf("\n\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 (scond < 0.1 || amax < small || amax > big) { /* Scale A */ if (uplo == Nag_Upper) for (j = 1; j <= n; ++j) for (i = MAX(1, j - kd); i <= j; ++i) AB_UPPER(i, j) *= s[i-1] * s[j-1]; else for (j = 1; j <= n; ++j) for (i = j; i <= MIN(n, j + kd); ++i) AB_LOWER(i, j) *= s[i-1] * s[j-1]; /* Print the scaled matrix using nag_band_real_mat_print (x04cec). */ fflush(stdout); nag_band_real_mat_print(order, n, n, kd1, kd2, 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 = 4; goto END; } } END: if (ab) NAG_FREE(ab); if (s) NAG_FREE(s); return exit_status; } #undef AB_UPPER #undef AB_LOWER