LAPACK
3.5.0
LAPACK: Linear Algebra PACKage

Go to the source code of this file.
Functions/Subroutines  
subroutine  dlarfb (SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, T, LDT, C, LDC, WORK, LDWORK) 
DLARFB applies a block reflector or its transpose to a general rectangular matrix. More...  
subroutine dlarfb  (  character  SIDE, 
character  TRANS,  
character  DIRECT,  
character  STOREV,  
integer  M,  
integer  N,  
integer  K,  
double precision, dimension( ldv, * )  V,  
integer  LDV,  
double precision, dimension( ldt, * )  T,  
integer  LDT,  
double precision, dimension( ldc, * )  C,  
integer  LDC,  
double precision, dimension( ldwork, * )  WORK,  
integer  LDWORK  
) 
DLARFB applies a block reflector or its transpose to a general rectangular matrix.
Download DLARFB + dependencies [TGZ] [ZIP] [TXT]DLARFB applies a real block reflector H or its transpose H**T to a real m by n matrix C, from either the left or the right.
[in]  SIDE  SIDE is CHARACTER*1 = 'L': apply H or H**T from the Left = 'R': apply H or H**T from the Right 
[in]  TRANS  TRANS is CHARACTER*1 = 'N': apply H (No transpose) = 'T': apply H**T (Transpose) 
[in]  DIRECT  DIRECT is CHARACTER*1 Indicates how H is formed from a product of elementary reflectors = 'F': H = H(1) H(2) . . . H(k) (Forward) = 'B': H = H(k) . . . H(2) H(1) (Backward) 
[in]  STOREV  STOREV is CHARACTER*1 Indicates how the vectors which define the elementary reflectors are stored: = 'C': Columnwise = 'R': Rowwise 
[in]  M  M is INTEGER The number of rows of the matrix C. 
[in]  N  N is INTEGER The number of columns of the matrix C. 
[in]  K  K is INTEGER The order of the matrix T (= the number of elementary reflectors whose product defines the block reflector). 
[in]  V  V is DOUBLE PRECISION array, dimension (LDV,K) if STOREV = 'C' (LDV,M) if STOREV = 'R' and SIDE = 'L' (LDV,N) if STOREV = 'R' and SIDE = 'R' The matrix V. See Further Details. 
[in]  LDV  LDV is INTEGER The leading dimension of the array V. If STOREV = 'C' and SIDE = 'L', LDV >= max(1,M); if STOREV = 'C' and SIDE = 'R', LDV >= max(1,N); if STOREV = 'R', LDV >= K. 
[in]  T  T is DOUBLE PRECISION array, dimension (LDT,K) The triangular k by k matrix T in the representation of the block reflector. 
[in]  LDT  LDT is INTEGER The leading dimension of the array T. LDT >= K. 
[in,out]  C  C is DOUBLE PRECISION array, dimension (LDC,N) On entry, the m by n matrix C. On exit, C is overwritten by H*C or H**T*C or C*H or C*H**T. 
[in]  LDC  LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M). 
[out]  WORK  WORK is DOUBLE PRECISION array, dimension (LDWORK,K) 
[in]  LDWORK  LDWORK is INTEGER The leading dimension of the array WORK. If SIDE = 'L', LDWORK >= max(1,N); if SIDE = 'R', LDWORK >= max(1,M). 
The shape of the matrix V and the storage of the vectors which define the H(i) is best illustrated by the following example with n = 5 and k = 3. The elements equal to 1 are not stored; the corresponding array elements are modified but restored on exit. The rest of the array is not used. DIRECT = 'F' and STOREV = 'C': DIRECT = 'F' and STOREV = 'R': V = ( 1 ) V = ( 1 v1 v1 v1 v1 ) ( v1 1 ) ( 1 v2 v2 v2 ) ( v1 v2 1 ) ( 1 v3 v3 ) ( v1 v2 v3 ) ( v1 v2 v3 ) DIRECT = 'B' and STOREV = 'C': DIRECT = 'B' and STOREV = 'R': V = ( v1 v2 v3 ) V = ( v1 v1 1 ) ( v1 v2 v3 ) ( v2 v2 v2 1 ) ( 1 v2 v3 ) ( v3 v3 v3 v3 1 ) ( 1 v3 ) ( 1 )
Definition at line 195 of file dlarfb.f.