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Problem Report 0206 Details

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Report 0206 Actions

    Problem Report Number 0206
    Submitter's Classification Test Suite problem
    State Resolved
    Resolution Test Suite Deficiency (TSD)
    Problem Resolution ID TSD.X.0206
    Raised 1995-04-12 08:00
    Updated 2003-03-13 08:00
    Published 1995-04-18 08:00
    Product Standard Internationalised System Calls and Libraries (XPG4)
    Certification Program The Open Brand certification program
    Test Suite VSX4 version 4.3.4
    Test Identification ANSI.os/maths/pow 5
    Problem Summary TSD4.206 pow(-1.0, 0.1) is not required to return 0 in this situation. The ANSI standard does not specify return values at all and the XPG4 standard does not require a specific return value for this scenario. ...
    Problem Text
    pow(-1.0, 0.1) is not required to return 0 in this situation. The
    ANSI standard does not specify return values at all and the XPG4
    standard does not require a specific return value for this scenario.
    No where in the "Return Value" section of the XPG4 standard is there a
    reference to the situation where the first argument to pow is negative
    and the second is non-integral. The description of the function
    implies this is invalid and the "Errors" section states that the errno
    will be set to EDOM when it occurs, but nothing is said about the
    return value.

    The test should be modified so that only the errno value is checked.
    Test Output
    /tset/ANSI.os/maths/pow/T.pow 5 Failed

    Test Description:
    pow(), when called with the first argument negative and second
    argument not an integer returns either zero or NaN, and sets errno to
    EDOM. In XPG3 mode, if NaN is returned errno may be left unset.

    Test Strategy:
    CALCULATE floating point constants using mlmachar().
    CREATE child
    REASSIGN stderr to /dev/null to avoid error output from maths
    functions.
    VERIFY pow(), when called with the first argument negative and
    second argument either
    a. returns zero and sets errno to EDOM;
    b. returns NaN and may set errno to EDOM.
    If in XPG3 mode, and NaN is returned, then errno is not tested.

    Test Information:
    pow(-1.0, 0.1) gave
    RETURN VALUES: expected: 0, observed: -7.23701e+75
    Bit Representation: expected value: \000\000\000\000\000\000\000\000
    Bit Representation: observed value: \377\377\377\377\377\377\377\377

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    This is accepted as a test suite fault. There has been a change between
    XPG3 and XPG4 behaviour which is not reflected in the test. The XPG4
    specification requires that an application set the errno to zero before
    calling pow() and check the errno subsequent to the call in order to
    identify domain errors of the nature specified above. The return value
    from pow() can take any value in these circumstances.

    It is recommended that this request be resolved by raising a test suite
    deficiency.

    Review Type SA Review
    Start Date null
    Completed null
    Status Complete
    Review Resolution Test Suite Deficiency (TSD)
    Review Conclusion
    This is an agreed Test Suite Deficiency.

    Problem Reporting System Options:

     

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