LAPACK 3.3.0

zlat2c.f

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00001       SUBROUTINE ZLAT2C( UPLO, N, A, LDA, SA, LDSA, INFO )
00002 *
00003 *  -- LAPACK PROTOTYPE auxiliary routine (version 3.1.2) --
00004 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00005 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00006 *     May 2007
00007 *
00008 *     .. Scalar Arguments ..
00009       CHARACTER          UPLO
00010       INTEGER            INFO, LDA, LDSA, N
00011 *     ..
00012 *     .. Array Arguments ..
00013       COMPLEX            SA( LDSA, * )
00014       COMPLEX*16         A( LDA, * )
00015 *     ..
00016 *
00017 *  Purpose
00018 *  =======
00019 *
00020 *  ZLAT2C converts a COMPLEX*16 triangular matrix, SA, to a COMPLEX
00021 *  triangular matrix, A.
00022 *
00023 *  RMAX is the overflow for the SINGLE PRECISION arithmetic
00024 *  ZLAT2C checks that all the entries of A are between -RMAX and
00025 *  RMAX. If not the convertion is aborted and a flag is raised.
00026 *
00027 *  This is an auxiliary routine so there is no argument checking.
00028 *
00029 *  Arguments
00030 *  =========
00031 *
00032 *  UPLO    (input) CHARACTER*1
00033 *          = 'U':  A is upper triangular;
00034 *          = 'L':  A is lower triangular.
00035 *
00036 *  N       (input) INTEGER
00037 *          The number of rows and columns of the matrix A.  N >= 0.
00038 *
00039 *  A       (input) COMPLEX*16 array, dimension (LDA,N)
00040 *          On entry, the N-by-N triangular coefficient matrix A.
00041 *
00042 *  LDA     (input) INTEGER
00043 *          The leading dimension of the array A.  LDA >= max(1,N).
00044 *
00045 *  SA      (output) COMPLEX array, dimension (LDSA,N)
00046 *          Only the UPLO part of SA is referenced.  On exit, if INFO=0,
00047 *          the N-by-N coefficient matrix SA; if INFO>0, the content of
00048 *          the UPLO part of SA is unspecified.
00049 *
00050 *  LDSA    (input) INTEGER
00051 *          The leading dimension of the array SA.  LDSA >= max(1,M).
00052 *
00053 *  INFO    (output) INTEGER
00054 *          = 0:  successful exit.
00055 *          = 1:  an entry of the matrix A is greater than the SINGLE
00056 *                PRECISION overflow threshold, in this case, the content
00057 *                of the UPLO part of SA in exit is unspecified.
00058 *
00059 *  =========
00060 *
00061 *     .. Local Scalars ..
00062       INTEGER            I, J
00063       DOUBLE PRECISION   RMAX
00064       LOGICAL            UPPER
00065 *     ..
00066 *     .. Intrinsic Functions ..
00067       INTRINSIC          DBLE, DIMAG
00068 *     ..
00069 *     .. External Functions ..
00070       REAL               SLAMCH
00071       LOGICAL            LSAME
00072       EXTERNAL           SLAMCH, LSAME
00073 *     ..
00074 *     .. Executable Statements ..
00075 *
00076       RMAX = SLAMCH( 'O' )
00077       UPPER = LSAME( UPLO, 'U' )
00078       IF( UPPER ) THEN
00079          DO 20 J = 1, N
00080             DO 10 I = 1, J
00081                IF( ( DBLE( A( I, J ) ).LT.-RMAX ) .OR.
00082      +             ( DBLE( A( I, J ) ).GT.RMAX ) .OR.
00083      +             ( DIMAG( A( I, J ) ).LT.-RMAX ) .OR.
00084      +             ( DIMAG( A( I, J ) ).GT.RMAX ) ) THEN
00085                   INFO = 1
00086                   GO TO 50
00087                END IF
00088                SA( I, J ) = A( I, J )
00089    10       CONTINUE
00090    20    CONTINUE
00091       ELSE
00092          DO 40 J = 1, N
00093             DO 30 I = J, N
00094                IF( ( DBLE( A( I, J ) ).LT.-RMAX ) .OR.
00095      +             ( DBLE( A( I, J ) ).GT.RMAX ) .OR.
00096      +             ( DIMAG( A( I, J ) ).LT.-RMAX ) .OR.
00097      +             ( DIMAG( A( I, J ) ).GT.RMAX ) ) THEN
00098                   INFO = 1
00099                   GO TO 50
00100                END IF
00101                SA( I, J ) = A( I, J )
00102    30       CONTINUE
00103    40    CONTINUE
00104       END IF
00105    50 CONTINUE
00106 *
00107       RETURN
00108 *
00109 *     End of ZLAT2C
00110 *
00111       END
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