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ilaenv.f(3)				      LAPACK				      ilaenv.f(3)

       ilaenv.f -

       INTEGER function ilaenv (ISPEC, NAME, OPTS, N1, N2, N3, N4)

Function/Subroutine Documentation
   INTEGER function ilaenv (integerISPEC, character*( * )NAME, character*( * )OPTS, integerN1,
       integerN2, integerN3, integerN4)


	    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.


		     Specifies the parameter to be returned as the value of
		     = 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 NaN arithmetic can be trusted not to trap
		     =11: infinity arithmetic can be trusted not to trap
		     12 <= ISPEC <= 16:
			  xHSEQR or one of its subroutines,
			  see IPARMQ for detailed explanation


		     NAME is CHARACTER*(*)
		     The name of the calling subroutine, in either upper case or
		     lower case.


		     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'.


		     N1 is INTEGER


		     N2 is INTEGER


		     N3 is INTEGER


		     N4 is INTEGER
		     Problem dimensions for the subroutine NAME; these may not all
		     be required.

	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

	   November 2011

       Further Details:

	     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 )

       Definition at line 163 of file ilaenv.f.

       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			      ilaenv.f(3)
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