LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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slarzb.f File Reference

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Functions/Subroutines

subroutine slarzb (SIDE, TRANS, DIRECT, STOREV, M, N, K, L, V, LDV, T, LDT, C, LDC, WORK, LDWORK)
 SLARZB applies a block reflector or its transpose to a general matrix.

Function/Subroutine Documentation

subroutine slarzb ( character  SIDE,
character  TRANS,
character  DIRECT,
character  STOREV,
integer  M,
integer  N,
integer  K,
integer  L,
real, dimension( ldv, * )  V,
integer  LDV,
real, dimension( ldt, * )  T,
integer  LDT,
real, dimension( ldc, * )  C,
integer  LDC,
real, dimension( ldwork, * )  WORK,
integer  LDWORK 
)

SLARZB applies a block reflector or its transpose to a general matrix.

Download SLARZB + dependencies [TGZ] [ZIP] [TXT]
Purpose: 
 SLARZB applies a real block reflector H or its transpose H**T to
 a real distributed M-by-N  C from the left or the right.

 Currently, only STOREV = 'R' and DIRECT = 'B' are supported.
Parameters:
[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)
          = 'C': 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, not supported yet)
          = '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                        (not supported yet)
          = '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]L
          L is INTEGER
          The number of columns of the matrix V containing the
          meaningful part of the Householder reflectors.
          If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.
[in]V
          V is REAL array, dimension (LDV,NV).
          If STOREV = 'C', NV = K; if STOREV = 'R', NV = L.
[in]LDV
          LDV is INTEGER
          The leading dimension of the array V.
          If STOREV = 'C', LDV >= L; if STOREV = 'R', LDV >= K.
[in]T
          T is REAL 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 REAL 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 REAL 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).
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Contributors:
A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
Further Details:

Definition at line 183 of file slarzb.f.

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