3 * =========== DOCUMENTATION ===========
5 * Online html documentation available at
6 * http://www.netlib.org/lapack/explore-html/
11 * SUBROUTINE CLAVHP( UPLO, TRANS, DIAG, N, NRHS, A, IPIV, B, LDB,
14 * .. Scalar Arguments ..
15 * CHARACTER DIAG, TRANS, UPLO
16 * INTEGER INFO, LDB, N, NRHS
18 * .. Array Arguments ..
20 * COMPLEX A( * ), B( LDB, * )
29 *> CLAVHP performs one of the matrix-vector operations
30 *> x := A*x or x := A^H*x,
31 *> where x is an N element vector and A is one of the factors
32 *> from the symmetric factorization computed by CHPTRF.
33 *> CHPTRF produces a factorization of the form
34 *> U * D * U^H or L * D * L^H,
35 *> where U (or L) is a product of permutation and unit upper (lower)
36 *> triangular matrices, U^H (or L^H) is the conjugate transpose of
37 *> U (or L), and D is Hermitian and block diagonal with 1 x 1 and
38 *> 2 x 2 diagonal blocks. The multipliers for the transformations
39 *> and the upper or lower triangular parts of the diagonal blocks
40 *> are stored columnwise in packed format in the linear array A.
42 *> If TRANS = 'N' or 'n', CLAVHP multiplies either by U or U * D
44 *> If TRANS = 'C' or 'c', CLAVHP multiplies either by U^H or D * U^H
45 *> (or L^H or D * L^H ).
53 *> On entry, UPLO specifies whether the triangular matrix
54 *> stored in A is upper or lower triangular.
55 *> UPLO = 'U' or 'u' The matrix is upper triangular.
56 *> UPLO = 'L' or 'l' The matrix is lower triangular.
59 *> TRANS - CHARACTER*1
60 *> On entry, TRANS specifies the operation to be performed as
62 *> TRANS = 'N' or 'n' x := A*x.
63 *> TRANS = 'C' or 'c' x := A^H*x.
67 *> On entry, DIAG specifies whether the diagonal blocks are
68 *> assumed to be unit matrices, as follows:
69 *> DIAG = 'U' or 'u' Diagonal blocks are unit matrices.
70 *> DIAG = 'N' or 'n' Diagonal blocks are non-unit.
74 *> On entry, N specifies the order of the matrix A.
75 *> N must be at least zero.
79 *> On entry, NRHS specifies the number of right hand sides,
80 *> i.e., the number of vectors x to be multiplied by A.
81 *> NRHS must be at least zero.
84 *> A - COMPLEX array, dimension( N*(N+1)/2 )
85 *> On entry, A contains a block diagonal matrix and the
86 *> multipliers of the transformations used to obtain it,
87 *> stored as a packed triangular matrix.
90 *> IPIV - INTEGER array, dimension( N )
91 *> On entry, IPIV contains the vector of pivot indices as
92 *> determined by CSPTRF or CHPTRF.
93 *> If IPIV( K ) = K, no interchange was done.
94 *> If IPIV( K ) <> K but IPIV( K ) > 0, then row K was inter-
95 *> changed with row IPIV( K ) and a 1 x 1 pivot block was used.
96 *> If IPIV( K ) < 0 and UPLO = 'U', then row K-1 was exchanged
97 *> with row | IPIV( K ) | and a 2 x 2 pivot block was used.
98 *> If IPIV( K ) < 0 and UPLO = 'L', then row K+1 was exchanged
99 *> with row | IPIV( K ) | and a 2 x 2 pivot block was used.
101 *> B - COMPLEX array, dimension( LDB, NRHS )
102 *> On entry, B contains NRHS vectors of length N.
103 *> On exit, B is overwritten with the product A * B.
106 *> On entry, LDB contains the leading dimension of B as
107 *> declared in the calling program. LDB must be at least
109 *> Unchanged on exit.
112 *> INFO is the error flag.
113 *> On exit, a value of 0 indicates a successful exit.
114 *> A negative value, say -K, indicates that the K-th argument
115 *> has an illegal value.
121 *> \author Univ. of Tennessee
122 *> \author Univ. of California Berkeley
123 *> \author Univ. of Colorado Denver
126 *> \date November 2011
128 *> \ingroup complex_lin
130 * =====================================================================
131 SUBROUTINE CLAVHP( UPLO, TRANS, DIAG, N, NRHS, A, IPIV, B, LDB,
134 * -- LAPACK test routine (version 3.4.0) --
135 * -- LAPACK is a software package provided by Univ. of Tennessee, --
136 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
139 * .. Scalar Arguments ..
140 CHARACTER DIAG, TRANS, UPLO
141 INTEGER INFO, LDB, N, NRHS
143 * .. Array Arguments ..
145 COMPLEX A( * ), B( LDB, * )
148 * =====================================================================
152 PARAMETER ( ONE = ( 1.0E+0, 0.0E+0 ) )
154 * .. Local Scalars ..
156 INTEGER J, K, KC, KCNEXT, KP
157 COMPLEX D11, D12, D21, D22, T1, T2
159 * .. External Functions ..
163 * .. External Subroutines ..
164 EXTERNAL CGEMV, CGERU, CLACGV, CSCAL, CSWAP, XERBLA
166 * .. Intrinsic Functions ..
167 INTRINSIC ABS, CONJG, MAX
169 * .. Executable Statements ..
171 * Test the input parameters.
174 IF( .NOT.LSAME( UPLO, 'U' ) .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
176 ELSE IF( .NOT.LSAME( TRANS, 'N' ) .AND. .NOT.LSAME( TRANS, 'C' ) )
179 ELSE IF( .NOT.LSAME( DIAG, 'U' ) .AND. .NOT.LSAME( DIAG, 'N' ) )
182 ELSE IF( N.LT.0 ) THEN
184 ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
188 CALL XERBLA( 'CLAVHP ', -INFO )
192 * Quick return if possible.
197 NOUNIT = LSAME( DIAG, 'N' )
198 *------------------------------------------
200 * Compute B := A * B (No transpose)
202 *------------------------------------------
203 IF( LSAME( TRANS, 'N' ) ) THEN
206 * where U = P(m)*inv(U(m))* ... *P(1)*inv(U(1))
208 IF( LSAME( UPLO, 'U' ) ) THEN
210 * Loop forward applying the transformations.
220 IF( IPIV( K ).GT.0 ) THEN
222 * Multiply by the diagonal element if forming U * D.
225 $ CALL CSCAL( NRHS, A( KC+K-1 ), B( K, 1 ), LDB )
227 * Multiply by P(K) * inv(U(K)) if K > 1.
231 * Apply the transformation.
233 CALL CGERU( K-1, NRHS, ONE, A( KC ), 1, B( K, 1 ),
234 $ LDB, B( 1, 1 ), LDB )
236 * Interchange if P(K) != I.
240 $ CALL CSWAP( NRHS, B( K, 1 ), LDB, B( KP, 1 ), LDB )
250 * Multiply by the diagonal block if forming U * D.
255 D12 = A( KCNEXT+K-1 )
260 B( K, J ) = D11*T1 + D12*T2
261 B( K+1, J ) = D21*T1 + D22*T2
265 * Multiply by P(K) * inv(U(K)) if K > 1.
269 * Apply the transformations.
271 CALL CGERU( K-1, NRHS, ONE, A( KC ), 1, B( K, 1 ),
272 $ LDB, B( 1, 1 ), LDB )
273 CALL CGERU( K-1, NRHS, ONE, A( KCNEXT ), 1,
274 $ B( K+1, 1 ), LDB, B( 1, 1 ), LDB )
276 * Interchange if P(K) != I.
278 KP = ABS( IPIV( K ) )
280 $ CALL CSWAP( NRHS, B( K, 1 ), LDB, B( KP, 1 ), LDB )
289 * where L = P(1)*inv(L(1))* ... *P(m)*inv(L(m)) .
293 * Loop backward applying the transformations to B.
296 KC = N*( N+1 ) / 2 + 1
302 * Test the pivot index. If greater than zero, a 1 x 1
303 * pivot was used, otherwise a 2 x 2 pivot was used.
305 IF( IPIV( K ).GT.0 ) THEN
309 * Multiply by the diagonal element if forming L * D.
312 $ CALL CSCAL( NRHS, A( KC ), B( K, 1 ), LDB )
314 * Multiply by P(K) * inv(L(K)) if K < N.
319 * Apply the transformation.
321 CALL CGERU( N-K, NRHS, ONE, A( KC+1 ), 1, B( K, 1 ),
322 $ LDB, B( K+1, 1 ), LDB )
324 * Interchange if a permutation was applied at the
325 * K-th step of the factorization.
328 $ CALL CSWAP( NRHS, B( K, 1 ), LDB, B( KP, 1 ), LDB )
336 KCNEXT = KC - ( N-K+2 )
338 * Multiply by the diagonal block if forming L * D.
348 B( K-1, J ) = D11*T1 + D12*T2
349 B( K, J ) = D21*T1 + D22*T2
353 * Multiply by P(K) * inv(L(K)) if K < N.
357 * Apply the transformation.
359 CALL CGERU( N-K, NRHS, ONE, A( KC+1 ), 1, B( K, 1 ),
360 $ LDB, B( K+1, 1 ), LDB )
361 CALL CGERU( N-K, NRHS, ONE, A( KCNEXT+2 ), 1,
362 $ B( K-1, 1 ), LDB, B( K+1, 1 ), LDB )
364 * Interchange if a permutation was applied at the
365 * K-th step of the factorization.
367 KP = ABS( IPIV( K ) )
369 $ CALL CSWAP( NRHS, B( K, 1 ), LDB, B( KP, 1 ), LDB )
377 *-------------------------------------------------
379 * Compute B := A^H * B (conjugate transpose)
381 *-------------------------------------------------
385 * where U = P(m)*inv(U(m))* ... *P(1)*inv(U(1))
386 * and U^H = inv(U^H(1))*P(1)* ... *inv(U^H(m))*P(m)
388 IF( LSAME( UPLO, 'U' ) ) THEN
390 * Loop backward applying the transformations.
393 KC = N*( N+1 ) / 2 + 1
400 IF( IPIV( K ).GT.0 ) THEN
403 * Interchange if P(K) != I.
407 $ CALL CSWAP( NRHS, B( K, 1 ), LDB, B( KP, 1 ), LDB )
409 * Apply the transformation:
410 * y := y - B' * conjg(x)
411 * where x is a column of A and y is a row of B.
413 CALL CLACGV( NRHS, B( K, 1 ), LDB )
414 CALL CGEMV( 'Conjugate', K-1, NRHS, ONE, B, LDB,
415 $ A( KC ), 1, ONE, B( K, 1 ), LDB )
416 CALL CLACGV( NRHS, B( K, 1 ), LDB )
419 $ CALL CSCAL( NRHS, A( KC+K-1 ), B( K, 1 ), LDB )
425 KCNEXT = KC - ( K-1 )
428 * Interchange if P(K) != I.
430 KP = ABS( IPIV( K ) )
432 $ CALL CSWAP( NRHS, B( K-1, 1 ), LDB, B( KP, 1 ),
435 * Apply the transformations.
437 CALL CLACGV( NRHS, B( K, 1 ), LDB )
438 CALL CGEMV( 'Conjugate', K-2, NRHS, ONE, B, LDB,
439 $ A( KC ), 1, ONE, B( K, 1 ), LDB )
440 CALL CLACGV( NRHS, B( K, 1 ), LDB )
442 CALL CLACGV( NRHS, B( K-1, 1 ), LDB )
443 CALL CGEMV( 'Conjugate', K-2, NRHS, ONE, B, LDB,
444 $ A( KCNEXT ), 1, ONE, B( K-1, 1 ), LDB )
445 CALL CLACGV( NRHS, B( K-1, 1 ), LDB )
448 * Multiply by the diagonal block if non-unit.
458 B( K-1, J ) = D11*T1 + D12*T2
459 B( K, J ) = D21*T1 + D22*T2
469 * where L = P(1)*inv(L(1))* ... *P(m)*inv(L(m))
470 * and L^H = inv(L(m))*P(m)* ... *inv(L(1))*P(1)
474 * Loop forward applying the L-transformations.
484 IF( IPIV( K ).GT.0 ) THEN
487 * Interchange if P(K) != I.
491 $ CALL CSWAP( NRHS, B( K, 1 ), LDB, B( KP, 1 ), LDB )
493 * Apply the transformation
495 CALL CLACGV( NRHS, B( K, 1 ), LDB )
496 CALL CGEMV( 'Conjugate', N-K, NRHS, ONE, B( K+1, 1 ),
497 $ LDB, A( KC+1 ), 1, ONE, B( K, 1 ), LDB )
498 CALL CLACGV( NRHS, B( K, 1 ), LDB )
501 $ CALL CSCAL( NRHS, A( KC ), B( K, 1 ), LDB )
508 KCNEXT = KC + N - K + 1
511 * Interchange if P(K) != I.
513 KP = ABS( IPIV( K ) )
515 $ CALL CSWAP( NRHS, B( K+1, 1 ), LDB, B( KP, 1 ),
518 * Apply the transformation
520 CALL CLACGV( NRHS, B( K+1, 1 ), LDB )
521 CALL CGEMV( 'Conjugate', N-K-1, NRHS, ONE,
522 $ B( K+2, 1 ), LDB, A( KCNEXT+1 ), 1, ONE,
524 CALL CLACGV( NRHS, B( K+1, 1 ), LDB )
526 CALL CLACGV( NRHS, B( K, 1 ), LDB )
527 CALL CGEMV( 'Conjugate', N-K-1, NRHS, ONE,
528 $ B( K+2, 1 ), LDB, A( KC+2 ), 1, ONE,
530 CALL CLACGV( NRHS, B( K, 1 ), LDB )
533 * Multiply by the diagonal block if non-unit.
543 B( K, J ) = D11*T1 + D12*T2
544 B( K+1, J ) = D21*T1 + D22*T2
547 KC = KCNEXT + ( N-K )