dlarzb (l)  Linux Man Pages
dlarzb: applies a real block reflector H or its transpose H**T to a real distributed MbyN C from the left or the right
NAME
DLARZB  applies a real block reflector H or its transpose H**T to a real distributed MbyN C from the left or the rightSYNOPSIS
 SUBROUTINE DLARZB(
 SIDE, TRANS, DIRECT, STOREV, M, N, K, L, V, LDV, T, LDT, C, LDC, WORK, LDWORK )
 CHARACTER DIRECT, SIDE, STOREV, TRANS
 INTEGER K, L, LDC, LDT, LDV, LDWORK, M, N
 DOUBLE PRECISION C( LDC, * ), T( LDT, * ), V( LDV, * ), WORK( LDWORK, * )
PURPOSE
DLARZB applies a real block reflector H or its transpose H**T to a real distributed MbyN C from the left or the right. Currently, only STOREV = aqRaq and DIRECT = aqBaq are supported.ARGUMENTS
 SIDE (input) CHARACTER*1

= aqLaq: apply H or Haq from the Left
= aqRaq: apply H or Haq from the Right  TRANS (input) CHARACTER*1

= aqNaq: apply H (No transpose)
= aqCaq: apply Haq (Transpose)  DIRECT (input) CHARACTER*1

Indicates how H is formed from a product of elementary
reflectors
= aqFaq: H = H(1) H(2) . . . H(k) (Forward, not supported yet)
= aqBaq: H = H(k) . . . H(2) H(1) (Backward)  STOREV (input) CHARACTER*1

Indicates how the vectors which define the elementary
reflectors are stored:
= aqCaq: Columnwise (not supported yet)
= aqRaq: Rowwise  M (input) INTEGER
 The number of rows of the matrix C.
 N (input) INTEGER
 The number of columns of the matrix C.
 K (input) INTEGER
 The order of the matrix T (= the number of elementary reflectors whose product defines the block reflector).
 L (input) INTEGER
 The number of columns of the matrix V containing the meaningful part of the Householder reflectors. If SIDE = aqLaq, M >= L >= 0, if SIDE = aqRaq, N >= L >= 0.
 V (input) DOUBLE PRECISION array, dimension (LDV,NV).
 If STOREV = aqCaq, NV = K; if STOREV = aqRaq, NV = L.
 LDV (input) INTEGER
 The leading dimension of the array V. If STOREV = aqCaq, LDV >= L; if STOREV = aqRaq, LDV >= K.
 T (input) DOUBLE PRECISION array, dimension (LDT,K)
 The triangular KbyK matrix T in the representation of the block reflector.
 LDT (input) INTEGER
 The leading dimension of the array T. LDT >= K.
 C (input/output) DOUBLE PRECISION array, dimension (LDC,N)
 On entry, the MbyN matrix C. On exit, C is overwritten by H*C or Haq*C or C*H or C*Haq.
 LDC (input) INTEGER
 The leading dimension of the array C. LDC >= max(1,M).
 WORK (workspace) DOUBLE PRECISION array, dimension (LDWORK,K)
 LDWORK (input) INTEGER
 The leading dimension of the array WORK. If SIDE = aqLaq, LDWORK >= max(1,N); if SIDE = aqRaq, LDWORK >= max(1,M).
FURTHER DETAILS
Based on contributions by