LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  sorgrq (M, N, K, A, LDA, TAU, WORK, LWORK, INFO) 
SORGRQ 
subroutine sorgrq  (  integer  M, 
integer  N,  
integer  K,  
real, dimension( lda, * )  A,  
integer  LDA,  
real, dimension( * )  TAU,  
real, dimension( * )  WORK,  
integer  LWORK,  
integer  INFO  
) 
SORGRQ
Download SORGRQ + dependencies [TGZ] [ZIP] [TXT]SORGRQ generates an MbyN real matrix Q with orthonormal rows, which is defined as the last M rows of a product of K elementary reflectors of order N Q = H(1) H(2) . . . H(k) as returned by SGERQF.
[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. N >= M. 
[in]  K  K is INTEGER The number of elementary reflectors whose product defines the matrix Q. M >= K >= 0. 
[in,out]  A  A is REAL array, dimension (LDA,N) On entry, the (mk+i)th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by SGERQF in the last k rows 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 REAL array, dimension (K) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGERQF. 
[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 >= max(1,M). For optimum performance LWORK >= M*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 sorgrq.f.