NAME dlarfb - apply a real block reflector H or its transpose H' to a real m by n matrix C, from either the left or the right SYNOPSIS SUBROUTINE DLARFB( SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, T, LDT, C, LDC, WORK, LDWORK ) #include <sunperf.h> void dlarfb(char side, char trans, char direct, char storev, int m, int n, int k, double *v, int ldv, double *t, int ldt, double *dc, int ldc) CHARACTER DIRECT, SIDE, STOREV, TRANS INTEGER K, LDC, LDT, LDV, LDWORK, M, N DOUBLE PRECISION C( LDC, * ), T( LDT, * ), V( LDV, * ), WORK( LDWORK, * ) ; PURPOSE DLARFB applies a real block reflector H or its transpose H' to a real m by n matrix C, from either the left or the right. ARGUMENTS SIDE (input) CHARACTER*1 = 'L': apply H or H' from the Left = 'R': apply H or H' from the Right TRANS (input) CHARACTER*1 = 'N': apply H (No transpose) = 'T': apply H' (Transpose) DIRECT (input) CHARACTER*1 Indicates how H is formed from a product of ele- mentary reflectors = 'F': H = H(1) H(2) . . . H(k) (Forward) = 'B': H = H(k) . . . H(2) H(1) (Backward) STOREV (input) CHARACTER*1 Indicates how the vectors which define the elemen- tary reflectors are stored: = 'C': Columnwise = 'R': Rowwise M (input) INTEGER The number of rows of the matrix C. N (input) INTEGER The number of columns of the matrix C. K (input) INTEGER The order of the matrix T (= the number of elemen- tary reflectors whose product defines the block reflector). V (input) 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. LDV (input) 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. T (input) DOUBLE PRECISION array, dimension (LDT,K) The triangular k by k matrix T in the representa- tion of the block reflector. LDT (input) INTEGER The leading dimension of the array T. LDT >= K. C (input/output) DOUBLE PRECISION array, dimension (LDC,N) On entry, the m by n matrix C. On exit, C is overwritten by H*C or H'*C or C*H or C*H'. LDC (input) INTEGER The leading dimension of the array C. LDA >= max(1,M). WORK (workspace) DOUBLE PRECISION array, dimension (LDWORK,K) LDWORK (input) INTEGER The leading dimension of the array WORK. If SIDE = 'L', LDWORK >= max(1,N); if SIDE = 'R', LDWORK >= max(1,M).
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