LAPACK  3.7.1
LAPACK: Linear Algebra PACKage
ilaenv.f
Go to the documentation of this file.
1 *> \brief \b ILAENV
2 *
3 * =========== DOCUMENTATION ===========
4 *
5 * Online html documentation available at
6 * http://www.netlib.org/lapack/explore-html/
7 *
8 *> \htmlonly
9 *> Download ILAENV + dependencies
10 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/ilaenv.f">
11 *> [TGZ]</a>
12 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/ilaenv.f">
13 *> [ZIP]</a>
14 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/ilaenv.f">
15 *> [TXT]</a>
16 *> \endhtmlonly
17 *
18 * Definition:
19 * ===========
20 *
21 * INTEGER FUNCTION ILAENV( ISPEC, NAME, OPTS, N1, N2, N3, N4 )
22 *
23 * .. Scalar Arguments ..
24 * CHARACTER*( * ) NAME, OPTS
25 * INTEGER ISPEC, N1, N2, N3, N4
26 * ..
27 *
28 *
29 *> \par Purpose:
30 * =============
31 *>
32 *> \verbatim
33 *>
34 *> ILAENV is called from the LAPACK routines to choose problem-dependent
35 *> parameters for the local environment. See ISPEC for a description of
36 *> the parameters.
37 *>
38 *> ILAENV returns an INTEGER
39 *> if ILAENV >= 0: ILAENV returns the value of the parameter specified by ISPEC
40 *> if ILAENV < 0: if ILAENV = -k, the k-th argument had an illegal value.
41 *>
42 *> This version provides a set of parameters which should give good,
43 *> but not optimal, performance on many of the currently available
44 *> computers. Users are encouraged to modify this subroutine to set
45 *> the tuning parameters for their particular machine using the option
46 *> and problem size information in the arguments.
47 *>
48 *> This routine will not function correctly if it is converted to all
49 *> lower case. Converting it to all upper case is allowed.
50 *> \endverbatim
51 *
52 * Arguments:
53 * ==========
54 *
55 *> \param[in] ISPEC
56 *> \verbatim
57 *> ISPEC is INTEGER
58 *> Specifies the parameter to be returned as the value of
59 *> ILAENV.
60 *> = 1: the optimal blocksize; if this value is 1, an unblocked
61 *> algorithm will give the best performance.
62 *> = 2: the minimum block size for which the block routine
63 *> should be used; if the usable block size is less than
64 *> this value, an unblocked routine should be used.
65 *> = 3: the crossover point (in a block routine, for N less
66 *> than this value, an unblocked routine should be used)
67 *> = 4: the number of shifts, used in the nonsymmetric
68 *> eigenvalue routines (DEPRECATED)
69 *> = 5: the minimum column dimension for blocking to be used;
70 *> rectangular blocks must have dimension at least k by m,
71 *> where k is given by ILAENV(2,...) and m by ILAENV(5,...)
72 *> = 6: the crossover point for the SVD (when reducing an m by n
73 *> matrix to bidiagonal form, if max(m,n)/min(m,n) exceeds
74 *> this value, a QR factorization is used first to reduce
75 *> the matrix to a triangular form.)
76 *> = 7: the number of processors
77 *> = 8: the crossover point for the multishift QR method
78 *> for nonsymmetric eigenvalue problems (DEPRECATED)
79 *> = 9: maximum size of the subproblems at the bottom of the
80 *> computation tree in the divide-and-conquer algorithm
81 *> (used by xGELSD and xGESDD)
82 *> =10: ieee NaN arithmetic can be trusted not to trap
83 *> =11: infinity arithmetic can be trusted not to trap
84 *> 12 <= ISPEC <= 16:
85 *> xHSEQR or related subroutines,
86 *> see IPARMQ for detailed explanation
87 *> \endverbatim
88 *>
89 *> \param[in] NAME
90 *> \verbatim
91 *> NAME is CHARACTER*(*)
92 *> The name of the calling subroutine, in either upper case or
93 *> lower case.
94 *> \endverbatim
95 *>
96 *> \param[in] OPTS
97 *> \verbatim
98 *> OPTS is CHARACTER*(*)
99 *> The character options to the subroutine NAME, concatenated
100 *> into a single character string. For example, UPLO = 'U',
101 *> TRANS = 'T', and DIAG = 'N' for a triangular routine would
102 *> be specified as OPTS = 'UTN'.
103 *> \endverbatim
104 *>
105 *> \param[in] N1
106 *> \verbatim
107 *> N1 is INTEGER
108 *> \endverbatim
109 *>
110 *> \param[in] N2
111 *> \verbatim
112 *> N2 is INTEGER
113 *> \endverbatim
114 *>
115 *> \param[in] N3
116 *> \verbatim
117 *> N3 is INTEGER
118 *> \endverbatim
119 *>
120 *> \param[in] N4
121 *> \verbatim
122 *> N4 is INTEGER
123 *> Problem dimensions for the subroutine NAME; these may not all
124 *> be required.
125 *> \endverbatim
126 *
127 * Authors:
128 * ========
129 *
130 *> \author Univ. of Tennessee
131 *> \author Univ. of California Berkeley
132 *> \author Univ. of Colorado Denver
133 *> \author NAG Ltd.
134 *
135 *> \date December 2016
136 *
137 *> \ingroup OTHERauxiliary
138 *
139 *> \par Further Details:
140 * =====================
141 *>
142 *> \verbatim
143 *>
144 *> The following conventions have been used when calling ILAENV from the
145 *> LAPACK routines:
146 *> 1) OPTS is a concatenation of all of the character options to
147 *> subroutine NAME, in the same order that they appear in the
148 *> argument list for NAME, even if they are not used in determining
149 *> the value of the parameter specified by ISPEC.
150 *> 2) The problem dimensions N1, N2, N3, N4 are specified in the order
151 *> that they appear in the argument list for NAME. N1 is used
152 *> first, N2 second, and so on, and unused problem dimensions are
153 *> passed a value of -1.
154 *> 3) The parameter value returned by ILAENV is checked for validity in
155 *> the calling subroutine. For example, ILAENV is used to retrieve
156 *> the optimal blocksize for STRTRI as follows:
157 *>
158 *> NB = ILAENV( 1, 'STRTRI', UPLO // DIAG, N, -1, -1, -1 )
159 *> IF( NB.LE.1 ) NB = MAX( 1, N )
160 *> \endverbatim
161 *>
162 * =====================================================================
163  INTEGER FUNCTION ilaenv( ISPEC, NAME, OPTS, N1, N2, N3, N4 )
164 *
165 * -- LAPACK auxiliary routine (version 3.7.0) --
166 * -- LAPACK is a software package provided by Univ. of Tennessee, --
167 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
168 * December 2016
169 *
170 * .. Scalar Arguments ..
171  CHARACTER*( * ) NAME, OPTS
172  INTEGER ISPEC, N1, N2, N3, N4
173 * ..
174 *
175 * =====================================================================
176 *
177 * .. Local Scalars ..
178  INTEGER I, IC, IZ, NB, NBMIN, NX
179  LOGICAL CNAME, SNAME
180  CHARACTER C1*1, C2*2, C4*2, C3*3, SUBNAM*6
181 * ..
182 * .. Intrinsic Functions ..
183  INTRINSIC char, ichar, int, min, real
184 * ..
185 * .. External Functions ..
186  INTEGER IEEECK, IPARMQ, IPARAM2STAGE
187  EXTERNAL ieeeck, iparmq, iparam2stage
188 * ..
189 * .. Executable Statements ..
190 *
191  GO TO ( 10, 10, 10, 80, 90, 100, 110, 120,
192  $ 130, 140, 150, 160, 160, 160, 160, 160,
193  $ 170, 170, 170, 170, 170 )ispec
194 *
195 * Invalid value for ISPEC
196 *
197  ilaenv = -1
198  RETURN
199 *
200  10 CONTINUE
201 *
202 * Convert NAME to upper case if the first character is lower case.
203 *
204  ilaenv = 1
205  subnam = name
206  ic = ichar( subnam( 1: 1 ) )
207  iz = ichar( 'Z' )
208  IF( iz.EQ.90 .OR. iz.EQ.122 ) THEN
209 *
210 * ASCII character set
211 *
212  IF( ic.GE.97 .AND. ic.LE.122 ) THEN
213  subnam( 1: 1 ) = char( ic-32 )
214  DO 20 i = 2, 6
215  ic = ichar( subnam( i: i ) )
216  IF( ic.GE.97 .AND. ic.LE.122 )
217  $ subnam( i: i ) = char( ic-32 )
218  20 CONTINUE
219  END IF
220 *
221  ELSE IF( iz.EQ.233 .OR. iz.EQ.169 ) THEN
222 *
223 * EBCDIC character set
224 *
225  IF( ( ic.GE.129 .AND. ic.LE.137 ) .OR.
226  $ ( ic.GE.145 .AND. ic.LE.153 ) .OR.
227  $ ( ic.GE.162 .AND. ic.LE.169 ) ) THEN
228  subnam( 1: 1 ) = char( ic+64 )
229  DO 30 i = 2, 6
230  ic = ichar( subnam( i: i ) )
231  IF( ( ic.GE.129 .AND. ic.LE.137 ) .OR.
232  $ ( ic.GE.145 .AND. ic.LE.153 ) .OR.
233  $ ( ic.GE.162 .AND. ic.LE.169 ) )subnam( i:
234  $ i ) = char( ic+64 )
235  30 CONTINUE
236  END IF
237 *
238  ELSE IF( iz.EQ.218 .OR. iz.EQ.250 ) THEN
239 *
240 * Prime machines: ASCII+128
241 *
242  IF( ic.GE.225 .AND. ic.LE.250 ) THEN
243  subnam( 1: 1 ) = char( ic-32 )
244  DO 40 i = 2, 6
245  ic = ichar( subnam( i: i ) )
246  IF( ic.GE.225 .AND. ic.LE.250 )
247  $ subnam( i: i ) = char( ic-32 )
248  40 CONTINUE
249  END IF
250  END IF
251 *
252  c1 = subnam( 1: 1 )
253  sname = c1.EQ.'S' .OR. c1.EQ.'D'
254  cname = c1.EQ.'C' .OR. c1.EQ.'Z'
255  IF( .NOT.( cname .OR. sname ) )
256  $ RETURN
257  c2 = subnam( 2: 3 )
258  c3 = subnam( 4: 6 )
259  c4 = c3( 2: 3 )
260 *
261  GO TO ( 50, 60, 70 )ispec
262 *
263  50 CONTINUE
264 *
265 * ISPEC = 1: block size
266 *
267 * In these examples, separate code is provided for setting NB for
268 * real and complex. We assume that NB will take the same value in
269 * single or double precision.
270 *
271  nb = 1
272 *
273  IF( c2.EQ.'GE' ) THEN
274  IF( c3.EQ.'TRF' ) THEN
275  IF( sname ) THEN
276  nb = 64
277  ELSE
278  nb = 64
279  END IF
280  ELSE IF( c3.EQ.'QRF' .OR. c3.EQ.'RQF' .OR. c3.EQ.'LQF' .OR.
281  $ c3.EQ.'QLF' ) THEN
282  IF( sname ) THEN
283  nb = 32
284  ELSE
285  nb = 32
286  END IF
287  ELSE IF( c3.EQ.'QR ') THEN
288  IF( n3 .EQ. 1) THEN
289  IF( sname ) THEN
290 * M*N
291  IF ((n1*n2.LE.131072).OR.(n1.LE.8192)) THEN
292  nb = n1
293  ELSE
294  nb = 32768/n2
295  END IF
296  ELSE
297  IF ((n1*n2.LE.131072).OR.(n1.LE.8192)) THEN
298  nb = n1
299  ELSE
300  nb = 32768/n2
301  END IF
302  END IF
303  ELSE
304  IF( sname ) THEN
305  nb = 1
306  ELSE
307  nb = 1
308  END IF
309  END IF
310  ELSE IF( c3.EQ.'LQ ') THEN
311  IF( n3 .EQ. 2) THEN
312  IF( sname ) THEN
313 * M*N
314  IF ((n1*n2.LE.131072).OR.(n1.LE.8192)) THEN
315  nb = n1
316  ELSE
317  nb = 32768/n2
318  END IF
319  ELSE
320  IF ((n1*n2.LE.131072).OR.(n1.LE.8192)) THEN
321  nb = n1
322  ELSE
323  nb = 32768/n2
324  END IF
325  END IF
326  ELSE
327  IF( sname ) THEN
328  nb = 1
329  ELSE
330  nb = 1
331  END IF
332  END IF
333  ELSE IF( c3.EQ.'HRD' ) THEN
334  IF( sname ) THEN
335  nb = 32
336  ELSE
337  nb = 32
338  END IF
339  ELSE IF( c3.EQ.'BRD' ) THEN
340  IF( sname ) THEN
341  nb = 32
342  ELSE
343  nb = 32
344  END IF
345  ELSE IF( c3.EQ.'TRI' ) THEN
346  IF( sname ) THEN
347  nb = 64
348  ELSE
349  nb = 64
350  END IF
351  END IF
352  ELSE IF( c2.EQ.'PO' ) THEN
353  IF( c3.EQ.'TRF' ) THEN
354  IF( sname ) THEN
355  nb = 64
356  ELSE
357  nb = 64
358  END IF
359  END IF
360  ELSE IF( c2.EQ.'SY' ) THEN
361  IF( c3.EQ.'TRF' ) THEN
362  IF( sname ) THEN
363  nb = 64
364  ELSE
365  nb = 64
366  END IF
367  ELSE IF( sname .AND. c3.EQ.'TRD' ) THEN
368  nb = 32
369  ELSE IF( sname .AND. c3.EQ.'GST' ) THEN
370  nb = 64
371  END IF
372  ELSE IF( cname .AND. c2.EQ.'HE' ) THEN
373  IF( c3.EQ.'TRF' ) THEN
374  nb = 64
375  ELSE IF( c3.EQ.'TRD' ) THEN
376  nb = 32
377  ELSE IF( c3.EQ.'GST' ) THEN
378  nb = 64
379  END IF
380  ELSE IF( sname .AND. c2.EQ.'OR' ) THEN
381  IF( c3( 1: 1 ).EQ.'G' ) THEN
382  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
383  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
384  $ THEN
385  nb = 32
386  END IF
387  ELSE IF( c3( 1: 1 ).EQ.'M' ) THEN
388  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
389  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
390  $ THEN
391  nb = 32
392  END IF
393  END IF
394  ELSE IF( cname .AND. c2.EQ.'UN' ) THEN
395  IF( c3( 1: 1 ).EQ.'G' ) THEN
396  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
397  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
398  $ THEN
399  nb = 32
400  END IF
401  ELSE IF( c3( 1: 1 ).EQ.'M' ) THEN
402  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
403  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
404  $ THEN
405  nb = 32
406  END IF
407  END IF
408  ELSE IF( c2.EQ.'GB' ) THEN
409  IF( c3.EQ.'TRF' ) THEN
410  IF( sname ) THEN
411  IF( n4.LE.64 ) THEN
412  nb = 1
413  ELSE
414  nb = 32
415  END IF
416  ELSE
417  IF( n4.LE.64 ) THEN
418  nb = 1
419  ELSE
420  nb = 32
421  END IF
422  END IF
423  END IF
424  ELSE IF( c2.EQ.'PB' ) THEN
425  IF( c3.EQ.'TRF' ) THEN
426  IF( sname ) THEN
427  IF( n2.LE.64 ) THEN
428  nb = 1
429  ELSE
430  nb = 32
431  END IF
432  ELSE
433  IF( n2.LE.64 ) THEN
434  nb = 1
435  ELSE
436  nb = 32
437  END IF
438  END IF
439  END IF
440  ELSE IF( c2.EQ.'TR' ) THEN
441  IF( c3.EQ.'TRI' ) THEN
442  IF( sname ) THEN
443  nb = 64
444  ELSE
445  nb = 64
446  END IF
447  ELSE IF ( c3.EQ.'EVC' ) THEN
448  IF( sname ) THEN
449  nb = 64
450  ELSE
451  nb = 64
452  END IF
453  END IF
454  ELSE IF( c2.EQ.'LA' ) THEN
455  IF( c3.EQ.'UUM' ) THEN
456  IF( sname ) THEN
457  nb = 64
458  ELSE
459  nb = 64
460  END IF
461  END IF
462  ELSE IF( sname .AND. c2.EQ.'ST' ) THEN
463  IF( c3.EQ.'EBZ' ) THEN
464  nb = 1
465  END IF
466  ELSE IF( c2.EQ.'GG' ) THEN
467  nb = 32
468  IF( c3.EQ.'HD3' ) THEN
469  IF( sname ) THEN
470  nb = 32
471  ELSE
472  nb = 32
473  END IF
474  END IF
475  END IF
476  ilaenv = nb
477  RETURN
478 *
479  60 CONTINUE
480 *
481 * ISPEC = 2: minimum block size
482 *
483  nbmin = 2
484  IF( c2.EQ.'GE' ) THEN
485  IF( c3.EQ.'QRF' .OR. c3.EQ.'RQF' .OR. c3.EQ.'LQF' .OR. c3.EQ.
486  $ 'QLF' ) THEN
487  IF( sname ) THEN
488  nbmin = 2
489  ELSE
490  nbmin = 2
491  END IF
492  ELSE IF( c3.EQ.'HRD' ) THEN
493  IF( sname ) THEN
494  nbmin = 2
495  ELSE
496  nbmin = 2
497  END IF
498  ELSE IF( c3.EQ.'BRD' ) THEN
499  IF( sname ) THEN
500  nbmin = 2
501  ELSE
502  nbmin = 2
503  END IF
504  ELSE IF( c3.EQ.'TRI' ) THEN
505  IF( sname ) THEN
506  nbmin = 2
507  ELSE
508  nbmin = 2
509  END IF
510  END IF
511  ELSE IF( c2.EQ.'SY' ) THEN
512  IF( c3.EQ.'TRF' ) THEN
513  IF( sname ) THEN
514  nbmin = 8
515  ELSE
516  nbmin = 8
517  END IF
518  ELSE IF( sname .AND. c3.EQ.'TRD' ) THEN
519  nbmin = 2
520  END IF
521  ELSE IF( cname .AND. c2.EQ.'HE' ) THEN
522  IF( c3.EQ.'TRD' ) THEN
523  nbmin = 2
524  END IF
525  ELSE IF( sname .AND. c2.EQ.'OR' ) THEN
526  IF( c3( 1: 1 ).EQ.'G' ) THEN
527  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
528  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
529  $ THEN
530  nbmin = 2
531  END IF
532  ELSE IF( c3( 1: 1 ).EQ.'M' ) THEN
533  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
534  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
535  $ THEN
536  nbmin = 2
537  END IF
538  END IF
539  ELSE IF( cname .AND. c2.EQ.'UN' ) THEN
540  IF( c3( 1: 1 ).EQ.'G' ) THEN
541  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
542  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
543  $ THEN
544  nbmin = 2
545  END IF
546  ELSE IF( c3( 1: 1 ).EQ.'M' ) THEN
547  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
548  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
549  $ THEN
550  nbmin = 2
551  END IF
552  END IF
553  ELSE IF( c2.EQ.'GG' ) THEN
554  nbmin = 2
555  IF( c3.EQ.'HD3' ) THEN
556  nbmin = 2
557  END IF
558  END IF
559  ilaenv = nbmin
560  RETURN
561 *
562  70 CONTINUE
563 *
564 * ISPEC = 3: crossover point
565 *
566  nx = 0
567  IF( c2.EQ.'GE' ) THEN
568  IF( c3.EQ.'QRF' .OR. c3.EQ.'RQF' .OR. c3.EQ.'LQF' .OR. c3.EQ.
569  $ 'QLF' ) THEN
570  IF( sname ) THEN
571  nx = 128
572  ELSE
573  nx = 128
574  END IF
575  ELSE IF( c3.EQ.'HRD' ) THEN
576  IF( sname ) THEN
577  nx = 128
578  ELSE
579  nx = 128
580  END IF
581  ELSE IF( c3.EQ.'BRD' ) THEN
582  IF( sname ) THEN
583  nx = 128
584  ELSE
585  nx = 128
586  END IF
587  END IF
588  ELSE IF( c2.EQ.'SY' ) THEN
589  IF( sname .AND. c3.EQ.'TRD' ) THEN
590  nx = 32
591  END IF
592  ELSE IF( cname .AND. c2.EQ.'HE' ) THEN
593  IF( c3.EQ.'TRD' ) THEN
594  nx = 32
595  END IF
596  ELSE IF( sname .AND. c2.EQ.'OR' ) THEN
597  IF( c3( 1: 1 ).EQ.'G' ) THEN
598  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
599  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
600  $ THEN
601  nx = 128
602  END IF
603  END IF
604  ELSE IF( cname .AND. c2.EQ.'UN' ) THEN
605  IF( c3( 1: 1 ).EQ.'G' ) THEN
606  IF( c4.EQ.'QR' .OR. c4.EQ.'RQ' .OR. c4.EQ.'LQ' .OR. c4.EQ.
607  $ 'QL' .OR. c4.EQ.'HR' .OR. c4.EQ.'TR' .OR. c4.EQ.'BR' )
608  $ THEN
609  nx = 128
610  END IF
611  END IF
612  ELSE IF( c2.EQ.'GG' ) THEN
613  nx = 128
614  IF( c3.EQ.'HD3' ) THEN
615  nx = 128
616  END IF
617  END IF
618  ilaenv = nx
619  RETURN
620 *
621  80 CONTINUE
622 *
623 * ISPEC = 4: number of shifts (used by xHSEQR)
624 *
625  ilaenv = 6
626  RETURN
627 *
628  90 CONTINUE
629 *
630 * ISPEC = 5: minimum column dimension (not used)
631 *
632  ilaenv = 2
633  RETURN
634 *
635  100 CONTINUE
636 *
637 * ISPEC = 6: crossover point for SVD (used by xGELSS and xGESVD)
638 *
639  ilaenv = int( REAL( MIN( N1, N2 ) )*1.6e0 )
640  RETURN
641 *
642  110 CONTINUE
643 *
644 * ISPEC = 7: number of processors (not used)
645 *
646  ilaenv = 1
647  RETURN
648 *
649  120 CONTINUE
650 *
651 * ISPEC = 8: crossover point for multishift (used by xHSEQR)
652 *
653  ilaenv = 50
654  RETURN
655 *
656  130 CONTINUE
657 *
658 * ISPEC = 9: maximum size of the subproblems at the bottom of the
659 * computation tree in the divide-and-conquer algorithm
660 * (used by xGELSD and xGESDD)
661 *
662  ilaenv = 25
663  RETURN
664 *
665  140 CONTINUE
666 *
667 * ISPEC = 10: ieee NaN arithmetic can be trusted not to trap
668 *
669 * ILAENV = 0
670  ilaenv = 1
671  IF( ilaenv.EQ.1 ) THEN
672  ilaenv = ieeeck( 1, 0.0, 1.0 )
673  END IF
674  RETURN
675 *
676  150 CONTINUE
677 *
678 * ISPEC = 11: infinity arithmetic can be trusted not to trap
679 *
680 * ILAENV = 0
681  ilaenv = 1
682  IF( ilaenv.EQ.1 ) THEN
683  ilaenv = ieeeck( 0, 0.0, 1.0 )
684  END IF
685  RETURN
686 *
687  160 CONTINUE
688 *
689 * 12 <= ISPEC <= 16: xHSEQR or related subroutines.
690 *
691  ilaenv = iparmq( ispec, name, opts, n1, n2, n3, n4 )
692  RETURN
693 *
694  170 CONTINUE
695 *
696 * 17 <= ISPEC <= 21: 2stage eigenvalues and SVD or related subroutines.
697 *
698  ilaenv = iparam2stage( ispec, name, opts, n1, n2, n3, n4 )
699  RETURN
700 *
701 * End of ILAENV
702 *
703  END
ilaenv
integer function ilaenv(ISPEC, NAME, OPTS, N1, N2, N3, N4)
ILAENV
Definition: tstiee.f:83