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Diffstat (limited to '2.3-1/src/fortran/lapack/zunghr.f')
| -rw-r--r-- | 2.3-1/src/fortran/lapack/zunghr.f | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/lapack/zunghr.f b/2.3-1/src/fortran/lapack/zunghr.f new file mode 100644 index 00000000..fcf32abf --- /dev/null +++ b/2.3-1/src/fortran/lapack/zunghr.f @@ -0,0 +1,165 @@ + SUBROUTINE ZUNGHR( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO ) +* +* -- LAPACK routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + INTEGER IHI, ILO, INFO, LDA, LWORK, N +* .. +* .. Array Arguments .. + COMPLEX*16 A( LDA, * ), TAU( * ), WORK( * ) +* .. +* +* Purpose +* ======= +* +* ZUNGHR generates a complex unitary matrix Q which is defined as the +* product of IHI-ILO elementary reflectors of order N, as returned by +* ZGEHRD: +* +* Q = H(ilo) H(ilo+1) . . . H(ihi-1). +* +* Arguments +* ========= +* +* N (input) INTEGER +* The order of the matrix Q. N >= 0. +* +* ILO (input) INTEGER +* IHI (input) INTEGER +* ILO and IHI must have the same values as in the previous call +* of ZGEHRD. Q is equal to the unit matrix except in the +* submatrix Q(ilo+1:ihi,ilo+1:ihi). +* 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. +* +* A (input/output) COMPLEX*16 array, dimension (LDA,N) +* On entry, the vectors which define the elementary reflectors, +* as returned by ZGEHRD. +* On exit, the N-by-N unitary matrix Q. +* +* LDA (input) INTEGER +* The leading dimension of the array A. LDA >= max(1,N). +* +* TAU (input) COMPLEX*16 array, dimension (N-1) +* TAU(i) must contain the scalar factor of the elementary +* reflector H(i), as returned by ZGEHRD. +* +* WORK (workspace/output) COMPLEX*16 array, dimension (MAX(1,LWORK)) +* On exit, if INFO = 0, WORK(1) returns the optimal LWORK. +* +* LWORK (input) INTEGER +* The dimension of the array WORK. LWORK >= IHI-ILO. +* For optimum performance LWORK >= (IHI-ILO)*NB, where NB is +* the optimal blocksize. +* +* If LWORK = -1, then a workspace query is assumed; the routine +* only calculates the optimal size of the WORK array, returns +* this value as the first entry of the WORK array, and no error +* message related to LWORK is issued by XERBLA. +* +* INFO (output) INTEGER +* = 0: successful exit +* < 0: if INFO = -i, the i-th argument had an illegal value +* +* ===================================================================== +* +* .. Parameters .. + COMPLEX*16 ZERO, ONE + PARAMETER ( ZERO = ( 0.0D+0, 0.0D+0 ), + $ ONE = ( 1.0D+0, 0.0D+0 ) ) +* .. +* .. Local Scalars .. + LOGICAL LQUERY + INTEGER I, IINFO, J, LWKOPT, NB, NH +* .. +* .. External Subroutines .. + EXTERNAL XERBLA, ZUNGQR +* .. +* .. External Functions .. + INTEGER ILAENV + EXTERNAL ILAENV +* .. +* .. Intrinsic Functions .. + INTRINSIC MAX, MIN +* .. +* .. Executable Statements .. +* +* Test the input arguments +* + INFO = 0 + NH = IHI - ILO + LQUERY = ( LWORK.EQ.-1 ) + IF( N.LT.0 ) THEN + INFO = -1 + ELSE IF( ILO.LT.1 .OR. ILO.GT.MAX( 1, N ) ) THEN + INFO = -2 + ELSE IF( IHI.LT.MIN( ILO, N ) .OR. IHI.GT.N ) THEN + INFO = -3 + ELSE IF( LDA.LT.MAX( 1, N ) ) THEN + INFO = -5 + ELSE IF( LWORK.LT.MAX( 1, NH ) .AND. .NOT.LQUERY ) THEN + INFO = -8 + END IF +* + IF( INFO.EQ.0 ) THEN + NB = ILAENV( 1, 'ZUNGQR', ' ', NH, NH, NH, -1 ) + LWKOPT = MAX( 1, NH )*NB + WORK( 1 ) = LWKOPT + END IF +* + IF( INFO.NE.0 ) THEN + CALL XERBLA( 'ZUNGHR', -INFO ) + RETURN + ELSE IF( LQUERY ) THEN + RETURN + END IF +* +* Quick return if possible +* + IF( N.EQ.0 ) THEN + WORK( 1 ) = 1 + RETURN + END IF +* +* Shift the vectors which define the elementary reflectors one +* column to the right, and set the first ilo and the last n-ihi +* rows and columns to those of the unit matrix +* + DO 40 J = IHI, ILO + 1, -1 + DO 10 I = 1, J - 1 + A( I, J ) = ZERO + 10 CONTINUE + DO 20 I = J + 1, IHI + A( I, J ) = A( I, J-1 ) + 20 CONTINUE + DO 30 I = IHI + 1, N + A( I, J ) = ZERO + 30 CONTINUE + 40 CONTINUE + DO 60 J = 1, ILO + DO 50 I = 1, N + A( I, J ) = ZERO + 50 CONTINUE + A( J, J ) = ONE + 60 CONTINUE + DO 80 J = IHI + 1, N + DO 70 I = 1, N + A( I, J ) = ZERO + 70 CONTINUE + A( J, J ) = ONE + 80 CONTINUE +* + IF( NH.GT.0 ) THEN +* +* Generate Q(ilo+1:ihi,ilo+1:ihi) +* + CALL ZUNGQR( NH, NH, NH, A( ILO+1, ILO+1 ), LDA, TAU( ILO ), + $ WORK, LWORK, IINFO ) + END IF + WORK( 1 ) = LWKOPT + RETURN +* +* End of ZUNGHR +* + END |