LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  sorghr (N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO) 
SORGHR 
subroutine sorghr  (  integer  N, 
integer  ILO,  
integer  IHI,  
real, dimension( lda, * )  A,  
integer  LDA,  
real, dimension( * )  TAU,  
real, dimension( * )  WORK,  
integer  LWORK,  
integer  INFO  
) 
SORGHR
Download SORGHR + dependencies [TGZ] [ZIP] [TXT]SORGHR generates a real orthogonal matrix Q which is defined as the product of IHIILO elementary reflectors of order N, as returned by SGEHRD: 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 SGEHRD. 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 REAL array, dimension (LDA,N) On entry, the vectors which define the elementary reflectors, as returned by SGEHRD. On exit, the NbyN orthogonal matrix Q. 
[in]  LDA  LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N). 
[in]  TAU  TAU is REAL array, dimension (N1) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGEHRD. 
[out]  WORK  WORK is REAL 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 sorghr.f.