DLARZB 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.

SIDE

          SIDE is CHARACTER*1


          = 'L': apply H or H**T from the Left


          = 'R': apply H or H**T from the Right

TRANS

          TRANS is CHARACTER*1


          = 'N': apply H (No transpose)


          = 'C': apply H**T (Transpose)

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)

STOREV

          STOREV is CHARACTER*1


          Indicates how the vectors which define the elementary


          reflectors are stored:


          = 'C': Columnwise                        (not supported yet)


          = 'R': Rowwise

M

          M is INTEGER


          The number of rows of the matrix C.

N

          N is INTEGER


          The number of columns of the matrix C.

K

          K is INTEGER


          The order of the matrix T (= the number of elementary


          reflectors whose product defines the block reflector).

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.

V

          V is DOUBLE PRECISION array, dimension (LDV,NV).


          If STOREV = 'C', NV = K; if STOREV = 'R', NV = L.

LDV

          LDV is INTEGER


          The leading dimension of the array V.


          If STOREV = 'C', LDV >= L; if STOREV = 'R', LDV >= K.

T

          T is DOUBLE PRECISION array, dimension (LDT,K)


          The triangular K-by-K matrix T in the representation of the


          block reflector.

LDT

          LDT is INTEGER


          The leading dimension of the array T. LDT >= K.

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.

LDC

          LDC is INTEGER


          The leading dimension of the array C. LDC >= max(1,M).

WORK

          WORK is DOUBLE PRECISION array, dimension (LDWORK,K)

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).

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

September 2012

A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA