dormhr (l)  Linux Manuals
dormhr: overwrites the general real MbyN matrix C with SIDE = aqLaq SIDE = aqRaq TRANS = aqNaq
NAME
DORMHR  overwrites the general real MbyN matrix C with SIDE = aqLaq SIDE = aqRaq TRANS = aqNaqSYNOPSIS
 SUBROUTINE DORMHR(
 SIDE, TRANS, M, N, ILO, IHI, A, LDA, TAU, C, LDC, WORK, LWORK, INFO )
 CHARACTER SIDE, TRANS
 INTEGER IHI, ILO, INFO, LDA, LDC, LWORK, M, N
 DOUBLE PRECISION A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
PURPOSE
DORMHR overwrites the general real MbyN matrix C with TRANS = aqTaq: Q**T * C C * Q**Twhere Q is a real orthogonal matrix of order nq, with nq = m if SIDE = aqLaq and nq = n if SIDE = aqRaq. Q is defined as the product of IHIILO elementary reflectors, as returned by DGEHRD:
Q = H(ilo) H(ilo+1) . . . H(ihi1).
ARGUMENTS
 SIDE (input) CHARACTER*1

= aqLaq: apply Q or Q**T from the Left;
= aqRaq: apply Q or Q**T from the Right.  TRANS (input) CHARACTER*1

= aqNaq: No transpose, apply Q;
= aqTaq: Transpose, apply Q**T.  M (input) INTEGER
 The number of rows of the matrix C. M >= 0.
 N (input) INTEGER
 The number of columns of the matrix C. N >= 0.
 ILO (input) INTEGER
 IHI (input) INTEGER ILO and IHI must have the same values as in the previous call of DGEHRD. Q is equal to the unit matrix except in the submatrix Q(ilo+1:ihi,ilo+1:ihi). If SIDE = aqLaq, then 1 <= ILO <= IHI <= M, if M > 0, and ILO = 1 and IHI = 0, if M = 0; if SIDE = aqRaq, then 1 <= ILO <= IHI <= N, if N > 0, and ILO = 1 and IHI = 0, if N = 0.
 A (input) DOUBLE PRECISION array, dimension
 (LDA,M) if SIDE = aqLaq (LDA,N) if SIDE = aqRaq The vectors which define the elementary reflectors, as returned by DGEHRD.
 LDA (input) INTEGER
 The leading dimension of the array A. LDA >= max(1,M) if SIDE = aqLaq; LDA >= max(1,N) if SIDE = aqRaq.
 TAU (input) DOUBLE PRECISION array, dimension
 (M1) if SIDE = aqLaq (N1) if SIDE = aqRaq TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DGEHRD.
 C (input/output) DOUBLE PRECISION array, dimension (LDC,N)
 On entry, the MbyN matrix C. On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q.
 LDC (input) INTEGER
 The leading dimension of the array C. LDC >= max(1,M).
 WORK (workspace/output) DOUBLE PRECISION array, dimension (MAX(1,LWORK))
 On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
 LWORK (input) INTEGER
 The dimension of the array WORK. If SIDE = aqLaq, LWORK >= max(1,N); if SIDE = aqRaq, LWORK >= max(1,M). For optimum performance LWORK >= N*NB if SIDE = aqLaq, and LWORK >= M*NB if SIDE = aqRaq, 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.
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value