 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] SMS: B23024      ]
 ]  G. W. ROOK        ]    BFS PROGRAM NOTE         ] DR:  106082      ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE (X)  USER NOTE ( ) ] DATE: 04/03/91   ]
 ]  RID (213)922-3308 ]      RELEASE NOTE ( )       ]                  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]   OI21 AND SUBS               ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]           MAJOR SOFTWARE AREA:            ] OPS MODES AFFECTED:     ]
 ]BSL( ) BSS( ) GNC(X) SEQ(X) SM/SP(X) IPL( )]      1,3,6              ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA:  RUNTIME LIBRARIES                               ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: N/A                                            ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ]         ARCCOS/ARCSIN PRECISION PROBLEMS                            ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]SOME LIBRARY ROUTINES (DACOS,DACOSH, DATANH) PERFORM COMPARES TO HARD]
 ]CODED DOUBLE PRECISION FLOATING POINT VALUES. IN ALL CASES IDENTIFIED]
 ]THE ROUTINE COMPARES AN INPUT VALUE TO A DOUBLE PRECISION ONE PLUS AN]
 ]EPSILON (1 + EPSILON EQUALS 411000000000FFFF IN FLOATING POINT HEX). ]
 ]HOWEVER, SOME NUMBERS SLIGHTLY LARGER THAN THIS VALUE, WHILE VALID   ]
 ]FOR THE ACCURACY OF THE AP101 FLOATING POINT CAPABILITIES, ARE       ]
 ]FLAGGED AS INVALID.  WHEN THE LIBRARY ROUTINES IN QUESTION DETECT    ]
 ]THIS SITUATION A GPC ERROR (B1) IS LOGGED AND A STANDARD FIX UP IS   ]
 ]THEN PERFORMED AND THE ROUTINE CONTINUES.  THE STANDARD FIX UP IS TO ]
 ]SET THE INPUT VALUE TO A ONE.  THE FIX UP IS CORRECT FOR THIS        ]
 ]SITUATION AND NO ERRONEOUS INPUTS ARE FED TO APPLICATION PROGRAMS.   ]
 ]DURING THE POWERED PORTION OF RTLS THERE IS A POSSIBILITY THAT THIS  ]
 ]CONDITION COULD RECUR REPEATEDLY.                                    ]
 ]_____________________________________________________________________]
 ] USER RESPONSE:                                                      ]
 ]                                                                     ]
 ]                                                                     ]
 ]   NO USER RESPONSE REQUIRED.                                        ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]RI: <S> R.B.DEAN FOR CHP  DATE 07/24/91]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:  ROBERT N. HINSON   DATE 08/22/91]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 03/10/92 ]
 ]PF MGR: DAVID STEPHENSON  DATE 08/21/91]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_____________________________________________________________________]
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