SGEMQRT overwrites the general real M-by-N matrix C with


                 SIDE = 'L'     SIDE = 'R'


 TRANS = 'N':      Q C            C Q


 TRANS = 'T':   Q**T C            C Q**T


 where Q is a real orthogonal matrix defined as the product of K


 elementary reflectors:


       Q = H(1) H(2) . . . H(K) = I - V T V**T


 generated using the compact WY representation as returned by SGEQRT.


 Q is of order M if SIDE = 'L' and of order N  if SIDE = 'R'.

SIDE

          SIDE is CHARACTER*1


          = 'L': apply Q or Q**T from the Left;


          = 'R': apply Q or Q**T from the Right.

TRANS

          TRANS is CHARACTER*1


          = 'N':  No transpose, apply Q;


          = 'T':  Transpose, apply Q**T.

M

          M is INTEGER


          The number of rows of the matrix C. M >= 0.

N

          N is INTEGER


          The number of columns of the matrix C. N >= 0.

K

          K is INTEGER


          The number of elementary reflectors whose product defines


          the matrix Q.


          If SIDE = 'L', M >= K >= 0;


          if SIDE = 'R', N >= K >= 0.

NB

          NB is INTEGER


          The block size used for the storage of T.  K >= NB >= 1.


          This must be the same value of NB used to generate T


          in CGEQRT.

V

          V is REAL array, dimension (LDV,K)


          The i-th column must contain the vector which defines the


          elementary reflector H(i), for i = 1,2,...,k, as returned by


          CGEQRT in the first K columns of its array argument A.

LDV

          LDV is INTEGER


          The leading dimension of the array V.


          If SIDE = 'L', LDA >= max(1,M);


          if SIDE = 'R', LDA >= max(1,N).

T

          T is REAL array, dimension (LDT,K)


          The upper triangular factors of the block reflectors


          as returned by CGEQRT, stored as a NB-by-N matrix.

LDT

          LDT is INTEGER


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

C

          C is REAL array, dimension (LDC,N)


          On entry, the M-by-N matrix C.


          On exit, C is overwritten by Q C, Q**T C, C Q**T or C Q.

LDC

          LDC is INTEGER


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

WORK

          WORK is REAL array. The dimension of WORK is


           N*NB if SIDE = 'L', or  M*NB if SIDE = 'R'.

INFO

          INFO is INTEGER


          = 0:  successful exit


          < 0:  if INFO = -i, the i-th argument had an illegal value

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NAG Ltd.

December 2016