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NAME ICMAX1 - find the index of the element whose real part has maximum absolute value SYNOPSIS INTEGER FUNCTION ICMAX1( N, CX, INCX ) INTEGER INCX, N COMPLEX CX( * ) PURPOSE ICMAX1 finds the index of the element whose real part has maximum absolute value. Based on ICAMAX from Level 1 BLAS. The change is to use the 'genuine' absolute value. Contributed by Nick Higham for use with CLACON. ARGUMENTS N (input) INTEGER The number of elements in the vector CX. CX (input) COMPLEX array, dimension (N) The vector whose elements will be summed. INCX (input) INTEGER The spacing between successive values of CX. INCX >= 1. NEXT LINE IS THE ONLY MODIFICATION. CODE FOR INCREMENT NOT EQUAL TO 1 CODE FOR INCREMENT EQUAL TO 1 End of ICMAX1

NAME ILAENV - i called from the LAPACK routines to choose problem-dependent parameters for the local environment SYNOPSIS INTEGER FUNCTION ILAENV( ISPEC, NAME, OPTS, N1, N2, N3, N4 ) CHARACTER*( * ) NAME, OPTS INTEGER ISPEC, N1, N2, N3, N4 PURPOSE ILAENV is called from the LAPACK routines to choose problem-dependent parameters for the local environment. See ISPEC for a description of the parameters. 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. ARGUMENTS ISPEC (input) 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 cross- over 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 eigen- value routines = 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 cross- over 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 and QZ methods for nonsymmetric eigenvalue problems. NAME (input) CHARACTER*(*) The name of the calling subroutine, in either upper case or lower case. OPTS (input) CHARACTER*(*) The character options to the subroutine NAME, con- catenated into a single character string. For exam- ple, UPLO = 'U', TRANS = 'T', and DIAG = 'N' for a triangular routine would be specified as OPTS = 'UTN'. N1 (input) INTEGER N2 (input) INTEGER N3 (input) INTEGER N4 (input) INTEGER Problem dimensions for the subrou- tine NAME; these may not all be required. >= 0: the value of the parameter specified by ISPEC < 0: if ILAENV = -k, the k-th argument had an ille- gal value. 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 dimen- sions 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 )