/* nag_dspgvx (f08tbc) Example Program. * * Copyright 2011 Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include int main(void) { /* Scalars */ double abstol, vl, vu; Integer i, il = 0, iu = 0, j, m, n, pdz; Integer exit_status = 0; /* Arrays */ double *ap = 0, *bp = 0, *w = 0, *z = 0; Integer *index = 0; char nag_enum_arg[40]; /* Nag Types */ NagError fail; Nag_OrderType order; Nag_UploType uplo; #ifdef NAG_COLUMN_MAJOR #define A_UPPER(I, J) ap[J*(J-1)/2 + I - 1] #define A_LOWER(I, J) ap[(2*n-J)*(J-1)/2 + I - 1] #define B_UPPER(I, J) bp[J*(J-1)/2 + I - 1] #define B_LOWER(I, J) bp[(2*n-J)*(J-1)/2 + I - 1] #define Z(I, J) z[(J-1)*pdz + I - 1] order = Nag_ColMajor; #else #define A_UPPER(I, J) ap[(2*n-I)*(I-1)/2 + J - 1] #define A_LOWER(I, J) ap[I*(I-1)/2 + J - 1] #define B_UPPER(I, J) bp[(2*n-I)*(I-1)/2 + J - 1] #define B_LOWER(I, J) bp[I*(I-1)/2 + J - 1] #define Z(I, J) z[(I-1)*pdz + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dspgvx (f08tbc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%*[^\n]", &n); if (n < 0) { printf("Invalid n\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); m = n; pdz = n; /* Allocate memory */ if (!(ap = NAG_ALLOC(n*(n+1)/2, double)) || !(bp = NAG_ALLOC(n*(n+1)/2, double)) || !(w = NAG_ALLOC(n, double)) || !(z = NAG_ALLOC(n * m, double)) || !(index = NAG_ALLOC(n, Integer))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the lower and upper bounds of the interval to be searched. */ scanf("%lf%lf%*[^\n]", &vl, &vu); /* Read the triangular parts of the matrices A and B from data file. */ if (uplo == Nag_Upper) { for (i = 1; i <= n; ++i) for (j = i; j <= n; ++j) scanf("%lf", &A_UPPER(i, j)); scanf("%*[^\n]"); for (i = 1; i <= n; ++i) for (j = i; j <= n; ++j) scanf("%lf", &B_UPPER(i, j)); } else if (uplo == Nag_Lower) { for (i = 1; i <= n; ++i) for (j = 1; j <= i; ++j) scanf("%lf", &A_LOWER(i, j)); scanf("%*[^\n]"); for (i = 1; i <= n; ++i) for (j = 1; j <= i; ++j) scanf("%lf", &B_LOWER(i, j)); } scanf("%*[^\n]"); /* use the default absolute error tolerance for eigenvalues. */ abstol = 0.0; /* Solve the generalized symmetric eigenvalue problem A*x = lambda*B*x * using nag_dspgvx (f08tbc). */ nag_dspgvx(order, 1, Nag_DoBoth, Nag_Interval, uplo, n, ap, bp, vl, vu, il, iu, abstol, &m, w, z, pdz, index, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dspgvx (f08tbc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Normalize the eigenvectors */ for(j=1; j<=m; j++) for(i=n; i>=1; i--) Z(i, j) = Z(i, j) / Z(1,j); /* Print eigensolution */ printf("Number of eigenvalues found =%5ld\n\n", m); printf(" Eigenvalues\n "); for (j = 0; j < m; ++j) printf(" %8.4f%s", w[j], j%8 == 7?"\n":""); printf("\n"); /* Print normalized vectors using nag_gen_real_mat_print (x04cac). */ fflush(stdout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, m, z, pdz, "Selected eigenvectors", 0, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } END: if (ap) NAG_FREE(ap); if (bp) NAG_FREE(bp); if (w) NAG_FREE(w); if (z) NAG_FREE(z); if (index) NAG_FREE(index); return exit_status; }