LAPACK 3.3.1 Linear Algebra PACKage

# cunmr3.f

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```00001       SUBROUTINE CUNMR3( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
00002      \$                   WORK, INFO )
00003 *
00004 *  -- LAPACK routine (version 3.3.1) --
00005 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00006 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00007 *  -- April 2011                                                      --
00008 *
00009 *     .. Scalar Arguments ..
00010       CHARACTER          SIDE, TRANS
00011       INTEGER            INFO, K, L, LDA, LDC, M, N
00012 *     ..
00013 *     .. Array Arguments ..
00014       COMPLEX            A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
00015 *     ..
00016 *
00017 *  Purpose
00018 *  =======
00019 *
00020 *  CUNMR3 overwrites the general complex m by n matrix C with
00021 *
00022 *        Q * C  if SIDE = 'L' and TRANS = 'N', or
00023 *
00024 *        Q**H* C  if SIDE = 'L' and TRANS = 'C', or
00025 *
00026 *        C * Q  if SIDE = 'R' and TRANS = 'N', or
00027 *
00028 *        C * Q**H if SIDE = 'R' and TRANS = 'C',
00029 *
00030 *  where Q is a complex unitary matrix defined as the product of k
00031 *  elementary reflectors
00032 *
00033 *        Q = H(1) H(2) . . . H(k)
00034 *
00035 *  as returned by CTZRZF. Q is of order m if SIDE = 'L' and of order n
00036 *  if SIDE = 'R'.
00037 *
00038 *  Arguments
00039 *  =========
00040 *
00041 *  SIDE    (input) CHARACTER*1
00042 *          = 'L': apply Q or Q**H from the Left
00043 *          = 'R': apply Q or Q**H from the Right
00044 *
00045 *  TRANS   (input) CHARACTER*1
00046 *          = 'N': apply Q  (No transpose)
00047 *          = 'C': apply Q**H (Conjugate transpose)
00048 *
00049 *  M       (input) INTEGER
00050 *          The number of rows of the matrix C. M >= 0.
00051 *
00052 *  N       (input) INTEGER
00053 *          The number of columns of the matrix C. N >= 0.
00054 *
00055 *  K       (input) INTEGER
00056 *          The number of elementary reflectors whose product defines
00057 *          the matrix Q.
00058 *          If SIDE = 'L', M >= K >= 0;
00059 *          if SIDE = 'R', N >= K >= 0.
00060 *
00061 *  L       (input) INTEGER
00062 *          The number of columns of the matrix A containing
00063 *          the meaningful part of the Householder reflectors.
00064 *          If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.
00065 *
00066 *  A       (input) COMPLEX array, dimension
00067 *                               (LDA,M) if SIDE = 'L',
00068 *                               (LDA,N) if SIDE = 'R'
00069 *          The i-th row must contain the vector which defines the
00070 *          elementary reflector H(i), for i = 1,2,...,k, as returned by
00071 *          CTZRZF in the last k rows of its array argument A.
00072 *          A is modified by the routine but restored on exit.
00073 *
00074 *  LDA     (input) INTEGER
00075 *          The leading dimension of the array A. LDA >= max(1,K).
00076 *
00077 *  TAU     (input) COMPLEX array, dimension (K)
00078 *          TAU(i) must contain the scalar factor of the elementary
00079 *          reflector H(i), as returned by CTZRZF.
00080 *
00081 *  C       (input/output) COMPLEX array, dimension (LDC,N)
00082 *          On entry, the m-by-n matrix C.
00083 *          On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.
00084 *
00085 *  LDC     (input) INTEGER
00086 *          The leading dimension of the array C. LDC >= max(1,M).
00087 *
00088 *  WORK    (workspace) COMPLEX array, dimension
00089 *                                   (N) if SIDE = 'L',
00090 *                                   (M) if SIDE = 'R'
00091 *
00092 *  INFO    (output) INTEGER
00093 *          = 0: successful exit
00094 *          < 0: if INFO = -i, the i-th argument had an illegal value
00095 *
00096 *  Further Details
00097 *  ===============
00098 *
00099 *  Based on contributions by
00100 *    A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
00101 *
00102 *  =====================================================================
00103 *
00104 *     .. Local Scalars ..
00105       LOGICAL            LEFT, NOTRAN
00106       INTEGER            I, I1, I2, I3, IC, JA, JC, MI, NI, NQ
00107       COMPLEX            TAUI
00108 *     ..
00109 *     .. External Functions ..
00110       LOGICAL            LSAME
00111       EXTERNAL           LSAME
00112 *     ..
00113 *     .. External Subroutines ..
00114       EXTERNAL           CLARZ, XERBLA
00115 *     ..
00116 *     .. Intrinsic Functions ..
00117       INTRINSIC          CONJG, MAX
00118 *     ..
00119 *     .. Executable Statements ..
00120 *
00121 *     Test the input arguments
00122 *
00123       INFO = 0
00124       LEFT = LSAME( SIDE, 'L' )
00125       NOTRAN = LSAME( TRANS, 'N' )
00126 *
00127 *     NQ is the order of Q
00128 *
00129       IF( LEFT ) THEN
00130          NQ = M
00131       ELSE
00132          NQ = N
00133       END IF
00134       IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
00135          INFO = -1
00136       ELSE IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'C' ) ) THEN
00137          INFO = -2
00138       ELSE IF( M.LT.0 ) THEN
00139          INFO = -3
00140       ELSE IF( N.LT.0 ) THEN
00141          INFO = -4
00142       ELSE IF( K.LT.0 .OR. K.GT.NQ ) THEN
00143          INFO = -5
00144       ELSE IF( L.LT.0 .OR. ( LEFT .AND. ( L.GT.M ) ) .OR.
00145      \$         ( .NOT.LEFT .AND. ( L.GT.N ) ) ) THEN
00146          INFO = -6
00147       ELSE IF( LDA.LT.MAX( 1, K ) ) THEN
00148          INFO = -8
00149       ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
00150          INFO = -11
00151       END IF
00152       IF( INFO.NE.0 ) THEN
00153          CALL XERBLA( 'CUNMR3', -INFO )
00154          RETURN
00155       END IF
00156 *
00157 *     Quick return if possible
00158 *
00159       IF( M.EQ.0 .OR. N.EQ.0 .OR. K.EQ.0 )
00160      \$   RETURN
00161 *
00162       IF( ( LEFT .AND. .NOT.NOTRAN .OR. .NOT.LEFT .AND. NOTRAN ) ) THEN
00163          I1 = 1
00164          I2 = K
00165          I3 = 1
00166       ELSE
00167          I1 = K
00168          I2 = 1
00169          I3 = -1
00170       END IF
00171 *
00172       IF( LEFT ) THEN
00173          NI = N
00174          JA = M - L + 1
00175          JC = 1
00176       ELSE
00177          MI = M
00178          JA = N - L + 1
00179          IC = 1
00180       END IF
00181 *
00182       DO 10 I = I1, I2, I3
00183          IF( LEFT ) THEN
00184 *
00185 *           H(i) or H(i)**H is applied to C(i:m,1:n)
00186 *
00187             MI = M - I + 1
00188             IC = I
00189          ELSE
00190 *
00191 *           H(i) or H(i)**H is applied to C(1:m,i:n)
00192 *
00193             NI = N - I + 1
00194             JC = I
00195          END IF
00196 *
00197 *        Apply H(i) or H(i)**H
00198 *
00199          IF( NOTRAN ) THEN
00200             TAUI = TAU( I )
00201          ELSE
00202             TAUI = CONJG( TAU( I ) )
00203          END IF
00204          CALL CLARZ( SIDE, MI, NI, L, A( I, JA ), LDA, TAUI,
00205      \$               C( IC, JC ), LDC, WORK )
00206 *
00207    10 CONTINUE
00208 *
00209       RETURN
00210 *
00211 *     End of CUNMR3
00212 *
00213       END
```