/* nag_dsbtrd (f08hec) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, k, kd, n, pdab, pdz, d_len, e_len; Integer exit_status=0; NagError fail; Nag_UploType uplo; Nag_OrderType order; /* Arrays */ char uplo_char[2]; double *ab=0, *d=0, *e=0, *z=0; #ifdef NAG_COLUMN_MAJOR #define AB_UPPER(I,J) ab[(J-1)*pdab + k + I - J - 1] #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 + k + J - I - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); Vprintf("f08hec Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%ld%*[^\n] ", &n, &kd); pdab = kd + 1; pdz = n; d_len = n; e_len = n-1; /* Allocate memory */ if ( !(ab = NAG_ALLOC(pdab * n, double)) || !(d = NAG_ALLOC(d_len, double)) || !(e = NAG_ALLOC(e_len, double)) || !(z = NAG_ALLOC(pdz * n, double)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A from data file */ Vscanf(" ' %1s '%*[^\n] ", uplo_char); if (*(unsigned char *)uplo_char == 'L') uplo = Nag_Lower; else if (*(unsigned char *)uplo_char == 'U') uplo = Nag_Upper; else { Vprintf("Unrecognised character for Nag_UploType type\n"); exit_status = -1; goto END; } k = kd + 1; if (uplo == Nag_Upper) { for (i = 1; i <= n; ++i) { for (j = i; j <= MIN(i+kd,n); ++j) Vscanf("%lf", &AB_UPPER(i,j)); } Vscanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = MAX(1,i-kd); j <= i; ++j) Vscanf("%lf", &AB_LOWER(i,j)); } Vscanf("%*[^\n] "); } /* Reduce A to tridiagonal form */ f08hec(order, Nag_FormQ, uplo, n, kd, ab, pdab, d, e, z, pdz, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from f08hec.\n%s\n", fail.message); exit_status = 1; goto END; } /* Calculate all the eigenvalues and eigenvectors of A */ f08jec(order, Nag_UpdateZ, n, d, e, z, pdz, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from f08jec.\n%s\n", fail.message); exit_status = 1; goto END; } /* Print eigenvalues and eigenvectors */ Vprintf("Eigenvalues\n"); for (i = 1; i <= n; ++i) Vprintf("%8.4f%s", d[i-1], i%8==0 ?"\n":" "); Vprintf("\n\n"); x04cac(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, z, pdz, "Eigenvectors", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from x04cac.\n%s\n", fail.message); exit_status = 1; goto END; } END: if (ab) NAG_FREE(ab); if (d) NAG_FREE(d); if (e) NAG_FREE(e); if (z) NAG_FREE(z); return exit_status; }