/* nag_dtrsyl (f08qhc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, m, n, pda, pdb, pdc, pdd, pde, pdf; Integer exit_status = 0; double alpha, beta, norm, scale; Nag_SignType sign = Nag_Minus; NagError fail; Nag_OrderType order; /* Arrays */ double *a = 0, *b = 0, *c = 0, *d = 0, *e = 0, *f = 0; #ifdef NAG_COLUMN_MAJOR #define A(I, J) a[(J-1)*pda + I - 1] #define B(I, J) b[(J-1)*pdb + I - 1] #define C(I, J) c[(J-1)*pdc + I - 1] #define D(I, J) d[(J-1)*pdd + I - 1] #define E(I, J) e[(J-1)*pde + I - 1] #define F(I, J) f[(J-1)*pdf + I - 1] order = Nag_ColMajor; #else #define A(I, J) a[(I-1)*pda + J - 1] #define B(I, J) b[(I-1)*pdb + J - 1] #define C(I, J) c[(I-1)*pdc + J - 1] #define D(I, J) d[(I-1)*pdd + J - 1] #define E(I, J) e[(I-1)*pde + J - 1] #define F(I, J) f[(I-1)*pdf + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dtrsyl (f08qhc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n] "); scanf("%ld%ld%*[^\n] ", &m, &n); #ifdef NAG_COLUMN_MAJOR pda = m; pdb = n; pdc = m; pdd = m; pde = m; pdf = m; #else pda = m; pdb = n; pdc = n; pdd = n; pde = n; pdf = n; #endif /* Allocate memory */ if (!(a = NAG_ALLOC(m * m, double)) || !(b = NAG_ALLOC(n * m, double)) || !(c = NAG_ALLOC(m * n, double)) || !(d = NAG_ALLOC(m * n, double)) || !(e = NAG_ALLOC(m * n, double)) || !(f = NAG_ALLOC(m * n, double)) ) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A, B and C from data file */ for (i = 1; i <= m; ++i) { for (j = 1; j <= m; ++j) scanf("%lf", &A(i, j)); } scanf("%*[^\n] "); for (i = 1; i <= n; ++i) { for (j = 1; j <= n; ++j) scanf("%lf", &B(i, j)); } scanf("%*[^\n] "); for (i = 1; i <= m; ++i) { for (j = 1; j <= n; ++j) scanf("%lf", &C(i, j)); } scanf("%*[^\n] "); /* Copy C into F */ for (i = 1; i <= m; ++i) { for (j = 1; j <= m; ++j) F(i, j) = C(i, j); } /* nag_gen_real_mat_print (x04cac): Print Matrix C. */ fflush(stdout); nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, m, n, c, pdc, "Matrix C", 0, &fail); printf("\n"); if (fail.code != NE_NOERROR) { printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } /* Reorder the Schur factorization T */ /* nag_dtrsyl (f08qhc). * Solve real Sylvester matrix equation AX + XB = C, A and B * are upper quasi-triangular or transposes */ nag_dtrsyl(order, Nag_NoTrans, Nag_NoTrans, sign, m, n, a, pda, b, pdb, c, pdc, &scale, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dtrsyl (f08qhc).\n%s\n", fail.message); exit_status = 1; goto END; } /* nag_dgemm (f16yac): Compute aC - (A*X + X*B*sign) from solution*/ /* and store in matrix E*/ alpha = 1.0; beta = 0.0; nag_dgemm(order, Nag_NoTrans, Nag_NoTrans, m, n, m, alpha, a, pda, c, pdc, beta, d, pdd, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgemm (f16yac).\n%s\n", fail.message); exit_status = 1; goto END; } if(sign == Nag_Minus) alpha = -1.0; else alpha = 1.0; beta = 1.0; nag_dgemm(order, Nag_NoTrans, Nag_NoTrans, m, n, n, alpha, c, pdc, b, pdb, beta, d, pdd, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dgemm (f16yac).\n%s\n", fail.message); exit_status = 1; goto END; } for(i=1; i<=m; i++) { for (j=1; j<=n; j++) E(i, j) = scale * F(i, j) - D(i, j); } /* nag_dge_norm (f16rac): Find norm of matrix E and print warning if */ /* it is too large */ nag_dge_norm(order, Nag_OneNorm, n, n, e, pde, &norm, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dge_norm (f16rac).\n%s\n", fail.message); exit_status = 1; goto END; } if (norm > pow(x02ajc(),0.8)) { printf("%s\n%s\n","Norm of aC - (A*X + X*B*sign) is much greater than 0.", "nag_dtrsyl (f08qhc) has failed."); } else { printf(" SCALE = %11.2e\n", scale); } END: NAG_FREE(a); NAG_FREE(b); NAG_FREE(c); NAG_FREE(d); NAG_FREE(e); NAG_FREE(f); return exit_status; }