LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  cunghr (N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO) 
CUNGHR 
subroutine cunghr  (  integer  N, 
integer  ILO,  
integer  IHI,  
complex, dimension( lda, * )  A,  
integer  LDA,  
complex, dimension( * )  TAU,  
complex, dimension( * )  WORK,  
integer  LWORK,  
integer  INFO  
) 
CUNGHR
Download CUNGHR + dependencies [TGZ] [ZIP] [TXT]CUNGHR generates a complex unitary matrix Q which is defined as the product of IHIILO elementary reflectors of order N, as returned by CGEHRD: Q = H(ilo) H(ilo+1) . . . H(ihi1).
[in]  N  N is INTEGER The order of the matrix Q. N >= 0. 
[in]  ILO  ILO is INTEGER 
[in]  IHI  IHI is INTEGER ILO and IHI must have the same values as in the previous call of CGEHRD. Q is equal to the unit matrix except in the submatrix Q(ilo+1:ihi,ilo+1:ihi). 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. 
[in,out]  A  A is COMPLEX array, dimension (LDA,N) On entry, the vectors which define the elementary reflectors, as returned by CGEHRD. On exit, the NbyN unitary matrix Q. 
[in]  LDA  LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N). 
[in]  TAU  TAU is COMPLEX array, dimension (N1) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CGEHRD. 
[out]  WORK  WORK is COMPLEX array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. 
[in]  LWORK  LWORK is INTEGER The dimension of the array WORK. LWORK >= IHIILO. For optimum performance LWORK >= (IHIILO)*NB, where NB is the optimal blocksize. If LWORK = 1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA. 
[out]  INFO  INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value 
Definition at line 127 of file cunghr.f.