f77 library problem

[Ian Hacking <ian at hackingi dot freeserve dot co dot uk>]

I seem to be having problems with the fortran library routine for ASIN.

I am using the Nov 1999  Gcc-2.95.2   version .

As  seen from the code, often the first value returned prints as
-1.#IND0    which seems to have a hex value of  0x0000000000000000  .
If the ASIN call is reissued immediately , it gives the correct answer.

Is this a hardware problem,  I am using an IBM Cyrix 333MHz processor,
or is it software ??

I must admit this has shaken my confidence , as I was getting real good
results from G77 .



FUNCTION DARSIN(ANGLE)
C
C   PURPOSE:
C   ======= Returns the Inverse Cosine of the argument Angle as Real*8.
C
C   INPUT ARGUMENTS:
C   ===============
C
 REAL*8 ANGLE
C
C   OUTPUT ARGUMENTS:
C   ================
C
 REAL*8 DARSIN
C
C   LOCAL VARIABLES:
C   ===============
 REAL*8 DTEMP
 INTEGER ITEMP(2)
 EQUIVALENCE (ITEMP(2),DTEMP)
C
C
C/////////////////////////////////////////////////////////////////////
C                                                                    |
C                   START OF EXECUTABLE CODE                         |
C                                                                    |
C/////////////////////////////////////////////////////////////////////
C
 DARSIN= ASIN(ANGLE)
 DTEMP = DARSIN
 IF (ITEMP(1).EQ.0 .AND .ITEMP(2).EQ.0 .AND.
     1  DABS(ANGLE).GT.1.D-9) THEN
          WRITE( 6,1002) ANGLE , DARSIN, ITEMP
1002  FORMAT( ' DARSIN , angles =',2F10.5,2Z9)
        DTEMP = ASIN(ANGLE)
   IF (ITEMP(1).EQ.0 .AND .ITEMP(2).EQ.0 )THEN
     WRITE(6,*) ' Wrong AGAIN '
     DARSIN = ANGLE
    ELSE
            DARSIN = DTEMP
   ENDIF
   WRITE(6,1003)ANGLE , DARSIN, ITEMP
1003  FORMAT( ' DARSIN updated   =',2F10.5,2Z9)
 ENDIF
 RETURN
 END


 DARSIN , angles =   0.33363  -1.#IND0        0        0
 DARSIN updated   =   0.33363   0.34015        0 5FBBFC76
 DARSIN , angles =   0.32692  -1.#IND0        0        0
 DARSIN updated   =   0.32692   0.33305        0 32A57E98
 DARSIN , angles =   0.33361  -1.#IND0        0        0
 DARSIN updated   =   0.33361   0.34014        0 F4EBBC2F
 DARSIN , angles =   0.32694  -1.#IND0        0        0
 DARSIN updated   =   0.32694   0.33307        0 181F0B06

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