LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  cungql (M, N, K, A, LDA, TAU, WORK, LWORK, INFO) 
CUNGQL 
subroutine cungql  (  integer  M, 
integer  N,  
integer  K,  
complex, dimension( lda, * )  A,  
integer  LDA,  
complex, dimension( * )  TAU,  
complex, dimension( * )  WORK,  
integer  LWORK,  
integer  INFO  
) 
CUNGQL
Download CUNGQL + dependencies [TGZ] [ZIP] [TXT]CUNGQL generates an MbyN complex matrix Q with orthonormal columns, which is defined as the last N columns of a product of K elementary reflectors of order M Q = H(k) . . . H(2) H(1) as returned by CGEQLF.
[in]  M  M is INTEGER The number of rows of the matrix Q. M >= 0. 
[in]  N  N is INTEGER The number of columns of the matrix Q. M >= N >= 0. 
[in]  K  K is INTEGER The number of elementary reflectors whose product defines the matrix Q. N >= K >= 0. 
[in,out]  A  A is COMPLEX array, dimension (LDA,N) On entry, the (nk+i)th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by CGEQLF in the last k columns of its array argument A. On exit, the MbyN matrix Q. 
[in]  LDA  LDA is INTEGER The first dimension of the array A. LDA >= max(1,M). 
[in]  TAU  TAU is COMPLEX array, dimension (K) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CGEQLF. 
[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 >= max(1,N). For optimum performance LWORK >= N*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 has an illegal value 
Definition at line 129 of file cungql.f.