# CentOS 7.0 - man page for dggbak (centos section 3)

dggbak.f(3) LAPACK dggbak.f(3)dggbak.fNAME-Functions/Subroutines subroutine dggbak (JOB, SIDE, N, ILO, IHI, LSCALE, RSCALE, M, V, LDV, INFO) DGGBAKSYNOPSISFunction/Subroutine Documentation subroutine dggbak (characterJOB, characterSIDE, integerN, integerILO, integerIHI, double precision, dimension( * )LSCALE, double precision, dimension( * )RSCALE, integerM, double precision, dimension( ldv, * )V, integerLDV, integerINFO) DGGBAK Purpose: DGGBAK forms the right or left eigenvectors of a real generalized eigenvalue problem A*x = lambda*B*x, by backward transformation on the computed eigenvectors of the balanced pair of matrices output by DGGBAL. Parameters: JOB JOB is CHARACTER*1 Specifies the type of backward transformation required: = 'N': do nothing, return immediately; = 'P': do backward transformation for permutation only; = 'S': do backward transformation for scaling only; = 'B': do backward transformations for both permutation and scaling. JOB must be the same as the argument JOB supplied to DGGBAL. SIDE SIDE is CHARACTER*1 = 'R': V contains right eigenvectors; = 'L': V contains left eigenvectors. N N is INTEGER The number of rows of the matrix V. N >= 0. ILO ILO is INTEGER IHI IHI is INTEGER The integers ILO and IHI determined by DGGBAL. 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. LSCALE LSCALE is DOUBLE PRECISION array, dimension (N) Details of the permutations and/or scaling factors applied to the left side of A and B, as returned by DGGBAL. RSCALE RSCALE is DOUBLE PRECISION array, dimension (N) Details of the permutations and/or scaling factors applied to the right side of A and B, as returned by DGGBAL. M M is INTEGER The number of columns of the matrix V. M >= 0. V V is DOUBLE PRECISION array, dimension (LDV,M) On entry, the matrix of right or left eigenvectors to be transformed, as returned by DTGEVC. On exit, V is overwritten by the transformed eigenvectors. LDV LDV is INTEGER The leading dimension of the matrix V. LDV >= max(1,N). INFO INFO is INTEGER = 0: successful exit. < 0: if INFO =, the i-th argument had an illegal value. Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: November 2011 Further Details: See R.C. Ward, Balancing the generalized eigenvalue problem, SIAM J. Sci. Stat. Comp. 2 (1981), 141-152. Definition at line 147 of file dggbak.f.-iAuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 dggbak.f(3)