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Cohérence Lapack.

    1: *> \brief \b IEEECK
    2: *
    3: *  =========== DOCUMENTATION ===========
    4: *
    5: * Online html documentation available at 
    6: *            http://www.netlib.org/lapack/explore-html/ 
    7: *
    8: *> \htmlonly
    9: *> Download IEEECK + dependencies 
   10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/ieeeck.f"> 
   11: *> [TGZ]</a> 
   12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/ieeeck.f"> 
   13: *> [ZIP]</a> 
   14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/ieeeck.f"> 
   15: *> [TXT]</a>
   16: *> \endhtmlonly 
   17: *
   18: *  Definition:
   19: *  ===========
   20: *
   21: *       INTEGER          FUNCTION IEEECK( ISPEC, ZERO, ONE )
   22: * 
   23: *       .. Scalar Arguments ..
   24: *       INTEGER            ISPEC
   25: *       REAL               ONE, ZERO
   26: *       ..
   27: *  
   28: *
   29: *> \par Purpose:
   30: *  =============
   31: *>
   32: *> \verbatim
   33: *>
   34: *> IEEECK is called from the ILAENV to verify that Infinity and
   35: *> possibly NaN arithmetic is safe (i.e. will not trap).
   36: *> \endverbatim
   37: *
   38: *  Arguments:
   39: *  ==========
   40: *
   41: *> \param[in] ISPEC
   42: *> \verbatim
   43: *>          ISPEC is INTEGER
   44: *>          Specifies whether to test just for inifinity arithmetic
   45: *>          or whether to test for infinity and NaN arithmetic.
   46: *>          = 0: Verify infinity arithmetic only.
   47: *>          = 1: Verify infinity and NaN arithmetic.
   48: *> \endverbatim
   49: *>
   50: *> \param[in] ZERO
   51: *> \verbatim
   52: *>          ZERO is REAL
   53: *>          Must contain the value 0.0
   54: *>          This is passed to prevent the compiler from optimizing
   55: *>          away this code.
   56: *> \endverbatim
   57: *>
   58: *> \param[in] ONE
   59: *> \verbatim
   60: *>          ONE is REAL
   61: *>          Must contain the value 1.0
   62: *>          This is passed to prevent the compiler from optimizing
   63: *>          away this code.
   64: *>
   65: *>  RETURN VALUE:  INTEGER
   66: *>          = 0:  Arithmetic failed to produce the correct answers
   67: *>          = 1:  Arithmetic produced the correct answers
   68: *> \endverbatim
   69: *
   70: *  Authors:
   71: *  ========
   72: *
   73: *> \author Univ. of Tennessee 
   74: *> \author Univ. of California Berkeley 
   75: *> \author Univ. of Colorado Denver 
   76: *> \author NAG Ltd. 
   77: *
   78: *> \date November 2011
   79: *
   80: *> \ingroup auxOTHERauxiliary
   81: *
   82: *  =====================================================================
   83:       INTEGER          FUNCTION IEEECK( ISPEC, ZERO, ONE )
   84: *
   85: *  -- LAPACK auxiliary routine (version 3.4.0) --
   86: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
   87: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
   88: *     November 2011
   89: *
   90: *     .. Scalar Arguments ..
   91:       INTEGER            ISPEC
   92:       REAL               ONE, ZERO
   93: *     ..
   94: *
   95: *  =====================================================================
   96: *
   97: *     .. Local Scalars ..
   98:       REAL               NAN1, NAN2, NAN3, NAN4, NAN5, NAN6, NEGINF,
   99:      $                   NEGZRO, NEWZRO, POSINF
  100: *     ..
  101: *     .. Executable Statements ..
  102:       IEEECK = 1
  103: *
  104:       POSINF = ONE / ZERO
  105:       IF( POSINF.LE.ONE ) THEN
  106:          IEEECK = 0
  107:          RETURN
  108:       END IF
  109: *
  110:       NEGINF = -ONE / ZERO
  111:       IF( NEGINF.GE.ZERO ) THEN
  112:          IEEECK = 0
  113:          RETURN
  114:       END IF
  115: *
  116:       NEGZRO = ONE / ( NEGINF+ONE )
  117:       IF( NEGZRO.NE.ZERO ) THEN
  118:          IEEECK = 0
  119:          RETURN
  120:       END IF
  121: *
  122:       NEGINF = ONE / NEGZRO
  123:       IF( NEGINF.GE.ZERO ) THEN
  124:          IEEECK = 0
  125:          RETURN
  126:       END IF
  127: *
  128:       NEWZRO = NEGZRO + ZERO
  129:       IF( NEWZRO.NE.ZERO ) THEN
  130:          IEEECK = 0
  131:          RETURN
  132:       END IF
  133: *
  134:       POSINF = ONE / NEWZRO
  135:       IF( POSINF.LE.ONE ) THEN
  136:          IEEECK = 0
  137:          RETURN
  138:       END IF
  139: *
  140:       NEGINF = NEGINF*POSINF
  141:       IF( NEGINF.GE.ZERO ) THEN
  142:          IEEECK = 0
  143:          RETURN
  144:       END IF
  145: *
  146:       POSINF = POSINF*POSINF
  147:       IF( POSINF.LE.ONE ) THEN
  148:          IEEECK = 0
  149:          RETURN
  150:       END IF
  151: *
  152: *
  153: *
  154: *
  155: *     Return if we were only asked to check infinity arithmetic
  156: *
  157:       IF( ISPEC.EQ.0 )
  158:      $   RETURN
  159: *
  160:       NAN1 = POSINF + NEGINF
  161: *
  162:       NAN2 = POSINF / NEGINF
  163: *
  164:       NAN3 = POSINF / POSINF
  165: *
  166:       NAN4 = POSINF*ZERO
  167: *
  168:       NAN5 = NEGINF*NEGZRO
  169: *
  170:       NAN6 = NAN5*ZERO
  171: *
  172:       IF( NAN1.EQ.NAN1 ) THEN
  173:          IEEECK = 0
  174:          RETURN
  175:       END IF
  176: *
  177:       IF( NAN2.EQ.NAN2 ) THEN
  178:          IEEECK = 0
  179:          RETURN
  180:       END IF
  181: *
  182:       IF( NAN3.EQ.NAN3 ) THEN
  183:          IEEECK = 0
  184:          RETURN
  185:       END IF
  186: *
  187:       IF( NAN4.EQ.NAN4 ) THEN
  188:          IEEECK = 0
  189:          RETURN
  190:       END IF
  191: *
  192:       IF( NAN5.EQ.NAN5 ) THEN
  193:          IEEECK = 0
  194:          RETURN
  195:       END IF
  196: *
  197:       IF( NAN6.EQ.NAN6 ) THEN
  198:          IEEECK = 0
  199:          RETURN
  200:       END IF
  201: *
  202:       RETURN
  203:       END