*> \brief \b ILAENV * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * *> \htmlonly *> Download ILAENV + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * Definition: * =========== * * INTEGER FUNCTION ILAENV( ISPEC, NAME, OPTS, N1, N2, N3, N4 ) * * .. Scalar Arguments .. * CHARACTER*( * ) NAME, OPTS * INTEGER ISPEC, N1, N2, N3, N4 * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> ILAENV is called from the LAPACK routines to choose problem-dependent *> parameters for the local environment. See ISPEC for a description of *> the parameters. *> *> ILAENV returns an INTEGER *> if ILAENV >= 0: ILAENV returns the value of the parameter specified by ISPEC *> if ILAENV < 0: if ILAENV = -k, the k-th argument had an illegal value. *> *> This version provides a set of parameters which should give good, *> but not optimal, performance on many of the currently available *> computers. Users are encouraged to modify this subroutine to set *> the tuning parameters for their particular machine using the option *> and problem size information in the arguments. *> *> This routine will not function correctly if it is converted to all *> lower case. Converting it to all upper case is allowed. *> \endverbatim * * Arguments: * ========== * *> \param[in] ISPEC *> \verbatim *> ISPEC is INTEGER *> Specifies the parameter to be returned as the value of *> ILAENV. *> = 1: the optimal blocksize; if this value is 1, an unblocked *> algorithm will give the best performance. *> = 2: the minimum block size for which the block routine *> should be used; if the usable block size is less than *> this value, an unblocked routine should be used. *> = 3: the crossover point (in a block routine, for N less *> than this value, an unblocked routine should be used) *> = 4: the number of shifts, used in the nonsymmetric *> eigenvalue routines (DEPRECATED) *> = 5: the minimum column dimension for blocking to be used; *> rectangular blocks must have dimension at least k by m, *> where k is given by ILAENV(2,...) and m by ILAENV(5,...) *> = 6: the crossover point for the SVD (when reducing an m by n *> matrix to bidiagonal form, if max(m,n)/min(m,n) exceeds *> this value, a QR factorization is used first to reduce *> the matrix to a triangular form.) *> = 7: the number of processors *> = 8: the crossover point for the multishift QR method *> for nonsymmetric eigenvalue problems (DEPRECATED) *> = 9: maximum size of the subproblems at the bottom of the *> computation tree in the divide-and-conquer algorithm *> (used by xGELSD and xGESDD) *> =10: ieee infinity and NaN arithmetic can be trusted not to trap *> =11: infinity arithmetic can be trusted not to trap *> 12 <= ISPEC <= 16: *> xHSEQR or related subroutines, *> see IPARMQ for detailed explanation *> \endverbatim *> *> \param[in] NAME *> \verbatim *> NAME is CHARACTER*(*) *> The name of the calling subroutine, in either upper case or *> lower case. *> \endverbatim *> *> \param[in] OPTS *> \verbatim *> OPTS is CHARACTER*(*) *> The character options to the subroutine NAME, concatenated *> into a single character string. For example, UPLO = 'U', *> TRANS = 'T', and DIAG = 'N' for a triangular routine would *> be specified as OPTS = 'UTN'. *> \endverbatim *> *> \param[in] N1 *> \verbatim *> N1 is INTEGER *> \endverbatim *> *> \param[in] N2 *> \verbatim *> N2 is INTEGER *> \endverbatim *> *> \param[in] N3 *> \verbatim *> N3 is INTEGER *> \endverbatim *> *> \param[in] N4 *> \verbatim *> N4 is INTEGER *> Problem dimensions for the subroutine NAME; these may not all *> be required. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup OTHERauxiliary * *> \par Further Details: * ===================== *> *> \verbatim *> *> The following conventions have been used when calling ILAENV from the *> LAPACK routines: *> 1) OPTS is a concatenation of all of the character options to *> subroutine NAME, in the same order that they appear in the *> argument list for NAME, even if they are not used in determining *> the value of the parameter specified by ISPEC. *> 2) The problem dimensions N1, N2, N3, N4 are specified in the order *> that they appear in the argument list for NAME. N1 is used *> first, N2 second, and so on, and unused problem dimensions are *> passed a value of -1. *> 3) The parameter value returned by ILAENV is checked for validity in *> the calling subroutine. For example, ILAENV is used to retrieve *> the optimal blocksize for STRTRI as follows: *> *> NB = ILAENV( 1, 'STRTRI', UPLO // DIAG, N, -1, -1, -1 ) *> IF( NB.LE.1 ) NB = MAX( 1, N ) *> \endverbatim *> * ===================================================================== INTEGER FUNCTION ILAENV( ISPEC, NAME, OPTS, N1, N2, N3, N4 ) * * -- LAPACK auxiliary routine -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. CHARACTER*( * ) NAME, OPTS INTEGER ISPEC, N1, N2, N3, N4 * .. * * ===================================================================== * * .. Local Scalars .. INTEGER I, IC, IZ, NB, NBMIN, NX LOGICAL CNAME, SNAME, TWOSTAGE CHARACTER C1*1, C2*2, C4*2, C3*3, SUBNAM*16 * .. * .. Intrinsic Functions .. INTRINSIC CHAR, ICHAR, INT, MIN, REAL * .. * .. External Functions .. INTEGER IEEECK, IPARMQ, IPARAM2STAGE EXTERNAL IEEECK, IPARMQ, IPARAM2STAGE * .. * .. Executable Statements .. * GO TO ( 10, 10, 10, 80, 90, 100, 110, 120, $ 130, 140, 150, 160, 160, 160, 160, 160)ISPEC * * Invalid value for ISPEC * ILAENV = -1 RETURN * 10 CONTINUE * * Convert NAME to upper case if the first character is lower case. * ILAENV = 1 SUBNAM = NAME IC = ICHAR( SUBNAM( 1: 1 ) ) IZ = ICHAR( 'Z' ) IF( IZ.EQ.90 .OR. IZ.EQ.122 ) THEN * * ASCII character set * IF( IC.GE.97 .AND. IC.LE.122 ) THEN SUBNAM( 1: 1 ) = CHAR( IC-32 ) DO 20 I = 2, 6 IC = ICHAR( SUBNAM( I: I ) ) IF( IC.GE.97 .AND. IC.LE.122 ) $ SUBNAM( I: I ) = CHAR( IC-32 ) 20 CONTINUE END IF * ELSE IF( IZ.EQ.233 .OR. IZ.EQ.169 ) THEN * * EBCDIC character set * IF( ( IC.GE.129 .AND. IC.LE.137 ) .OR. $ ( IC.GE.145 .AND. IC.LE.153 ) .OR. $ ( IC.GE.162 .AND. IC.LE.169 ) ) THEN SUBNAM( 1: 1 ) = CHAR( IC+64 ) DO 30 I = 2, 6 IC = ICHAR( SUBNAM( I: I ) ) IF( ( IC.GE.129 .AND. IC.LE.137 ) .OR. $ ( IC.GE.145 .AND. IC.LE.153 ) .OR. $ ( IC.GE.162 .AND. IC.LE.169 ) )SUBNAM( I: $ I ) = CHAR( IC+64 ) 30 CONTINUE END IF * ELSE IF( IZ.EQ.218 .OR. IZ.EQ.250 ) THEN * * Prime machines: ASCII+128 * IF( IC.GE.225 .AND. IC.LE.250 ) THEN SUBNAM( 1: 1 ) = CHAR( IC-32 ) DO 40 I = 2, 6 IC = ICHAR( SUBNAM( I: I ) ) IF( IC.GE.225 .AND. IC.LE.250 ) $ SUBNAM( I: I ) = CHAR( IC-32 ) 40 CONTINUE END IF END IF * C1 = SUBNAM( 1: 1 ) SNAME = C1.EQ.'S' .OR. C1.EQ.'D' CNAME = C1.EQ.'C' .OR. C1.EQ.'Z' IF( .NOT.( CNAME .OR. SNAME ) ) $ RETURN C2 = SUBNAM( 2: 3 ) C3 = SUBNAM( 4: 6 ) C4 = C3( 2: 3 ) TWOSTAGE = LEN( SUBNAM ).GE.11 $ .AND. SUBNAM( 11: 11 ).EQ.'2' * GO TO ( 50, 60, 70 )ISPEC * 50 CONTINUE * * ISPEC = 1: block size * * In these examples, separate code is provided for setting NB for * real and complex. We assume that NB will take the same value in * single or double precision. * NB = 1 * IF( SUBNAM(2:6).EQ.'LAORH' ) THEN * * This is for *LAORHR_GETRFNP routine * IF( SNAME ) THEN NB = 32 ELSE NB = 32 END IF ELSE IF( C2.EQ.'GE' ) THEN IF( C3.EQ.'TRF' ) THEN IF( SNAME ) THEN NB = 64 ELSE NB = 64 END IF ELSE IF( C3.EQ.'QRF' .OR. C3.EQ.'RQF' .OR. C3.EQ.'LQF' .OR. $ C3.EQ.'QLF' ) THEN IF( SNAME ) THEN NB = 32 ELSE NB = 32 END IF ELSE IF( C3.EQ.'QR ') THEN IF( N3 .EQ. 1) THEN IF( SNAME ) THEN * M*N IF ((N1*N2.LE.131072).OR.(N1.LE.8192)) THEN NB = N1 ELSE NB = 32768/N2 END IF ELSE IF ((N1*N2.LE.131072).OR.(N1.LE.8192)) THEN NB = N1 ELSE NB = 32768/N2 END IF END IF ELSE IF( SNAME ) THEN NB = 1 ELSE NB = 1 END IF END IF ELSE IF( C3.EQ.'LQ ') THEN IF( N3 .EQ. 2) THEN IF( SNAME ) THEN * M*N IF ((N1*N2.LE.131072).OR.(N1.LE.8192)) THEN NB = N1 ELSE NB = 32768/N2 END IF ELSE IF ((N1*N2.LE.131072).OR.(N1.LE.8192)) THEN NB = N1 ELSE NB = 32768/N2 END IF END IF ELSE IF( SNAME ) THEN NB = 1 ELSE NB = 1 END IF END IF ELSE IF( C3.EQ.'HRD' ) THEN IF( SNAME ) THEN NB = 32 ELSE NB = 32 END IF ELSE IF( C3.EQ.'BRD' ) THEN IF( SNAME ) THEN NB = 32 ELSE NB = 32 END IF ELSE IF( C3.EQ.'TRI' ) THEN IF( SNAME ) THEN NB = 64 ELSE NB = 64 END IF END IF ELSE IF( C2.EQ.'PO' ) THEN IF( C3.EQ.'TRF' ) THEN IF( SNAME ) THEN NB = 64 ELSE NB = 64 END IF END IF ELSE IF( C2.EQ.'SY' ) THEN IF( C3.EQ.'TRF' ) THEN IF( SNAME ) THEN IF( TWOSTAGE ) THEN NB = 192 ELSE NB = 64 END IF ELSE IF( TWOSTAGE ) THEN NB = 192 ELSE NB = 64 END IF END IF ELSE IF( SNAME .AND. C3.EQ.'TRD' ) THEN NB = 32 ELSE IF( SNAME .AND. C3.EQ.'GST' ) THEN NB = 64 END IF ELSE IF( CNAME .AND. C2.EQ.'HE' ) THEN IF( C3.EQ.'TRF' ) THEN IF( TWOSTAGE ) THEN NB = 192 ELSE NB = 64 END IF ELSE IF( C3.EQ.'TRD' ) THEN NB = 32 ELSE IF( C3.EQ.'GST' ) THEN NB = 64 END IF ELSE IF( SNAME .AND. C2.EQ.'OR' ) THEN IF( C3( 1: 1 ).EQ.'G' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NB = 32 END IF ELSE IF( C3( 1: 1 ).EQ.'M' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NB = 32 END IF END IF ELSE IF( CNAME .AND. C2.EQ.'UN' ) THEN IF( C3( 1: 1 ).EQ.'G' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NB = 32 END IF ELSE IF( C3( 1: 1 ).EQ.'M' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NB = 32 END IF END IF ELSE IF( C2.EQ.'GB' ) THEN IF( C3.EQ.'TRF' ) THEN IF( SNAME ) THEN IF( N4.LE.64 ) THEN NB = 1 ELSE NB = 32 END IF ELSE IF( N4.LE.64 ) THEN NB = 1 ELSE NB = 32 END IF END IF END IF ELSE IF( C2.EQ.'PB' ) THEN IF( C3.EQ.'TRF' ) THEN IF( SNAME ) THEN IF( N2.LE.64 ) THEN NB = 1 ELSE NB = 32 END IF ELSE IF( N2.LE.64 ) THEN NB = 1 ELSE NB = 32 END IF END IF END IF ELSE IF( C2.EQ.'TR' ) THEN IF( C3.EQ.'TRI' ) THEN IF( SNAME ) THEN NB = 64 ELSE NB = 64 END IF ELSE IF ( C3.EQ.'EVC' ) THEN IF( SNAME ) THEN NB = 64 ELSE NB = 64 END IF END IF ELSE IF( C2.EQ.'LA' ) THEN IF( C3.EQ.'UUM' ) THEN IF( SNAME ) THEN NB = 64 ELSE NB = 64 END IF END IF ELSE IF( SNAME .AND. C2.EQ.'ST' ) THEN IF( C3.EQ.'EBZ' ) THEN NB = 1 END IF ELSE IF( C2.EQ.'GG' ) THEN NB = 32 IF( C3.EQ.'HD3' ) THEN IF( SNAME ) THEN NB = 32 ELSE NB = 32 END IF END IF END IF ILAENV = NB RETURN * 60 CONTINUE * * ISPEC = 2: minimum block size * NBMIN = 2 IF( C2.EQ.'GE' ) THEN IF( C3.EQ.'QRF' .OR. C3.EQ.'RQF' .OR. C3.EQ.'LQF' .OR. C3.EQ. $ 'QLF' ) THEN IF( SNAME ) THEN NBMIN = 2 ELSE NBMIN = 2 END IF ELSE IF( C3.EQ.'HRD' ) THEN IF( SNAME ) THEN NBMIN = 2 ELSE NBMIN = 2 END IF ELSE IF( C3.EQ.'BRD' ) THEN IF( SNAME ) THEN NBMIN = 2 ELSE NBMIN = 2 END IF ELSE IF( C3.EQ.'TRI' ) THEN IF( SNAME ) THEN NBMIN = 2 ELSE NBMIN = 2 END IF END IF ELSE IF( C2.EQ.'SY' ) THEN IF( C3.EQ.'TRF' ) THEN IF( SNAME ) THEN NBMIN = 8 ELSE NBMIN = 8 END IF ELSE IF( SNAME .AND. C3.EQ.'TRD' ) THEN NBMIN = 2 END IF ELSE IF( CNAME .AND. C2.EQ.'HE' ) THEN IF( C3.EQ.'TRD' ) THEN NBMIN = 2 END IF ELSE IF( SNAME .AND. C2.EQ.'OR' ) THEN IF( C3( 1: 1 ).EQ.'G' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NBMIN = 2 END IF ELSE IF( C3( 1: 1 ).EQ.'M' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NBMIN = 2 END IF END IF ELSE IF( CNAME .AND. C2.EQ.'UN' ) THEN IF( C3( 1: 1 ).EQ.'G' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NBMIN = 2 END IF ELSE IF( C3( 1: 1 ).EQ.'M' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NBMIN = 2 END IF END IF ELSE IF( C2.EQ.'GG' ) THEN NBMIN = 2 IF( C3.EQ.'HD3' ) THEN NBMIN = 2 END IF END IF ILAENV = NBMIN RETURN * 70 CONTINUE * * ISPEC = 3: crossover point * NX = 0 IF( C2.EQ.'GE' ) THEN IF( C3.EQ.'QRF' .OR. C3.EQ.'RQF' .OR. C3.EQ.'LQF' .OR. C3.EQ. $ 'QLF' ) THEN IF( SNAME ) THEN NX = 128 ELSE NX = 128 END IF ELSE IF( C3.EQ.'HRD' ) THEN IF( SNAME ) THEN NX = 128 ELSE NX = 128 END IF ELSE IF( C3.EQ.'BRD' ) THEN IF( SNAME ) THEN NX = 128 ELSE NX = 128 END IF END IF ELSE IF( C2.EQ.'SY' ) THEN IF( SNAME .AND. C3.EQ.'TRD' ) THEN NX = 32 END IF ELSE IF( CNAME .AND. C2.EQ.'HE' ) THEN IF( C3.EQ.'TRD' ) THEN NX = 32 END IF ELSE IF( SNAME .AND. C2.EQ.'OR' ) THEN IF( C3( 1: 1 ).EQ.'G' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NX = 128 END IF END IF ELSE IF( CNAME .AND. C2.EQ.'UN' ) THEN IF( C3( 1: 1 ).EQ.'G' ) THEN IF( C4.EQ.'QR' .OR. C4.EQ.'RQ' .OR. C4.EQ.'LQ' .OR. C4.EQ. $ 'QL' .OR. C4.EQ.'HR' .OR. C4.EQ.'TR' .OR. C4.EQ.'BR' ) $ THEN NX = 128 END IF END IF ELSE IF( C2.EQ.'GG' ) THEN NX = 128 IF( C3.EQ.'HD3' ) THEN NX = 128 END IF END IF ILAENV = NX RETURN * 80 CONTINUE * * ISPEC = 4: number of shifts (used by xHSEQR) * ILAENV = 6 RETURN * 90 CONTINUE * * ISPEC = 5: minimum column dimension (not used) * ILAENV = 2 RETURN * 100 CONTINUE * * ISPEC = 6: crossover point for SVD (used by xGELSS and xGESVD) * ILAENV = INT( REAL( MIN( N1, N2 ) )*1.6E0 ) RETURN * 110 CONTINUE * * ISPEC = 7: number of processors (not used) * ILAENV = 1 RETURN * 120 CONTINUE * * ISPEC = 8: crossover point for multishift (used by xHSEQR) * ILAENV = 50 RETURN * 130 CONTINUE * * ISPEC = 9: maximum size of the subproblems at the bottom of the * computation tree in the divide-and-conquer algorithm * (used by xGELSD and xGESDD) * ILAENV = 25 RETURN * 140 CONTINUE * * ISPEC = 10: ieee and infinity NaN arithmetic can be trusted not to trap * * ILAENV = 0 ILAENV = 1 IF( ILAENV.EQ.1 ) THEN ILAENV = IEEECK( 1, 0.0, 1.0 ) END IF RETURN * 150 CONTINUE * * ISPEC = 11: ieee infinity arithmetic can be trusted not to trap * * ILAENV = 0 ILAENV = 1 IF( ILAENV.EQ.1 ) THEN ILAENV = IEEECK( 0, 0.0, 1.0 ) END IF RETURN * 160 CONTINUE * * 12 <= ISPEC <= 16: xHSEQR or related subroutines. * ILAENV = IPARMQ( ISPEC, NAME, OPTS, N1, N2, N3, N4 ) RETURN * * End of ILAENV * END