Re: How would Ariane 5 have behaved if overflow checking were not turned off?

["robin" <robin51@dodo.com.au>]

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Stephen Leake wrote in message <82d3lsvqw7.fsf@stephe-leake.org>...
>Elias Salomão Helou Neto <eshneto@gmail.com> writes:
>
>> I have followed the (quite lenghty) on a topic, IIRC, about bitwise
>> operators, which eventually lead to people mentioning the Ariane 5
>> case.
>>
>> Since then I have been wondering. If compiler checking where actually
>> turned on, what would have happened? How could it avoid the disaster?
>
>Just to remind people; the real problem was that Ariane 4 code was
>reused on Ariane 5, without carefully considering the design, also
>without adequate testing.
>
>Ariane 5 is a bigger rocket; it has bigger accelerations.

It does?  The Report doesn't say anything about that.
What it *does* say is that the horizontal velocity was greater
in Ariane 5 than Ariane 4.
That doesn't mean that the acceleration upwards was greater.

> The range for
>accelerations in the code, which was correct for Ariane 4, was incorrect
>for Ariane 5.
>
>No amount of "defensive programming" can handle such a fundamental
>design error.

The remedy could have been as simple as substituting the
largest magnitude integer (with appropriate sign).