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

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Functions/Subroutines

subroutine ztprfb (SIDE, TRANS, DIRECT, STOREV, M, N, K, L, V, LDV, T, LDT, A, LDA, B, LDB, WORK, LDWORK)
 ZTPRFB applies a real or complex "triangular-pentagonal" blocked reflector to a real or complex matrix, which is composed of two blocks.

Function/Subroutine Documentation

subroutine ztprfb ( character  SIDE,
character  TRANS,
character  DIRECT,
character  STOREV,
integer  M,
integer  N,
integer  K,
integer  L,
complex*16, dimension( ldv, * )  V,
integer  LDV,
complex*16, dimension( ldt, * )  T,
integer  LDT,
complex*16, dimension( lda, * )  A,
integer  LDA,
complex*16, dimension( ldb, * )  B,
integer  LDB,
complex*16, dimension( ldwork, * )  WORK,
integer  LDWORK 
)

ZTPRFB applies a real or complex "triangular-pentagonal" blocked reflector to a real or complex matrix, which is composed of two blocks.

Download ZTPRFB + dependencies [TGZ] [ZIP] [TXT]
Purpose:
 ZTPRFB applies a complex "triangular-pentagonal" block reflector H or its 
 conjugate transpose H**H to a complex matrix C, which is composed of two 
 blocks A and B, either from the left or right.
Parameters:
[in]SIDE
          SIDE is CHARACTER*1
          = 'L': apply H or H**H from the Left
          = 'R': apply H or H**H from the Right
[in]TRANS
          TRANS is CHARACTER*1
          = 'N': apply H (No transpose)
          = 'C': apply H**H (Conjugate 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': Columns
          = 'R': Rows
[in]M
          M is INTEGER
          The number of rows of the matrix B.  
          M >= 0.
[in]N
          N is INTEGER
          The number of columns of the matrix B.  
          N >= 0.
[in]K
          K is INTEGER
          The order of the matrix T, i.e. the number of elementary
          reflectors whose product defines the block reflector.  
          K >= 0.
[in]L
          L is INTEGER
          The order of the trapezoidal part of V.  
          K >= L >= 0.  See Further Details.
[in]V
          V is COMPLEX*16 array, dimension
                                (LDV,K) if STOREV = 'C'
                                (LDV,M) if STOREV = 'R' and SIDE = 'L'
                                (LDV,N) if STOREV = 'R' and SIDE = 'R'
          The pentagonal matrix V, which contains the elementary reflectors
          H(1), H(2), ..., H(K).  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 COMPLEX*16 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]A
          A is COMPLEX*16 array, dimension
          (LDA,N) if SIDE = 'L' or (LDA,K) if SIDE = 'R'
          On entry, the K-by-N or M-by-K matrix A.
          On exit, A is overwritten by the corresponding block of 
          H*C or H**H*C or C*H or C*H**H.  See Futher Details.
[in]LDA
          LDA is INTEGER
          The leading dimension of the array A. 
          If SIDE = 'L', LDC >= max(1,K);
          If SIDE = 'R', LDC >= max(1,M). 
[in,out]B
          B is COMPLEX*16 array, dimension (LDB,N)
          On entry, the M-by-N matrix B.
          On exit, B is overwritten by the corresponding block of
          H*C or H**H*C or C*H or C*H**H.  See Further Details.
[in]LDB
          LDB is INTEGER
          The leading dimension of the array B. 
          LDB >= max(1,M).
[out]WORK
          WORK is COMPLEX*16 array, dimension
          (LDWORK,N) if SIDE = 'L',
          (LDWORK,K) if SIDE = 'R'.
[in]LDWORK
          LDWORK is INTEGER
          The leading dimension of the array WORK.
          If SIDE = 'L', LDWORK >= K; 
          if SIDE = 'R', LDWORK >= M.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Further Details:
  The matrix C is a composite matrix formed from blocks A and B.
  The block B is of size M-by-N; if SIDE = 'R', A is of size M-by-K, 
  and if SIDE = 'L', A is of size K-by-N.

  If SIDE = 'R' and DIRECT = 'F', C = [A B].

  If SIDE = 'L' and DIRECT = 'F', C = [A] 
                                      [B].

  If SIDE = 'R' and DIRECT = 'B', C = [B A].

  If SIDE = 'L' and DIRECT = 'B', C = [B]
                                      [A]. 

  The pentagonal matrix V is composed of a rectangular block V1 and a 
  trapezoidal block V2.  The size of the trapezoidal block is determined by 
  the parameter L, where 0<=L<=K.  If L=K, the V2 block of V is triangular;
  if L=0, there is no trapezoidal block, thus V = V1 is rectangular.

  If DIRECT = 'F' and STOREV = 'C':  V = [V1]
                                         [V2]
     - V2 is upper trapezoidal (first L rows of K-by-K upper triangular)

  If DIRECT = 'F' and STOREV = 'R':  V = [V1 V2]

     - V2 is lower trapezoidal (first L columns of K-by-K lower triangular)

  If DIRECT = 'B' and STOREV = 'C':  V = [V2]
                                         [V1]
     - V2 is lower trapezoidal (last L rows of K-by-K lower triangular)

  If DIRECT = 'B' and STOREV = 'R':  V = [V2 V1]
    
     - V2 is upper trapezoidal (last L columns of K-by-K upper triangular)

  If STOREV = 'C' and SIDE = 'L', V is M-by-K with V2 L-by-K.

  If STOREV = 'C' and SIDE = 'R', V is N-by-K with V2 L-by-K.

  If STOREV = 'R' and SIDE = 'L', V is K-by-M with V2 K-by-L.

  If STOREV = 'R' and SIDE = 'R', V is K-by-N with V2 K-by-L.

Definition at line 251 of file ztprfb.f.

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