Parenthesis

[Sean Kelly]

Walter Bright wrote:
> NN wrote:
>> What about removing unuseful parenthesis in 'if', 'for', 'while' ?
> 
> Because having redundancies in the syntax helps prevent bugs such as the 
> following:
> 
>> As told by Fred Webb in alt.folklore.computers in 1990:
>>
>> |  I worked at Nasa during the summer of 1963.  The group I was working
>> |  in was doing preliminary work on the Mission Control Center computer
>> |  systems and programs.  My office mate had the job of testing out an
>> |  orbit computation program which had been used during the Mercury
>> |  flights.  Running some test data with known answers through it, he was
>> |  getting answers that were close, but not accurate enough.  So, he
>> |  started looking for numerical problems in the algorithm, checking to
>> |  make sure his tests data was really correct, etc.
>> |
>> |  After a couple of weeks with no results, he came across a DO
>> |  statement, in the form:
>> |       DO 10 I=1.10
>> |  This statement was interpreted by the compiler (correctly) as:
>> |       DO10I = 1.10
>> |  The programmer had clearly intended:
>> |       DO 10 I = 1, 10
>> |
>> |  After changing the `.' to a `,' the program results were correct to
>> |  the desired accuracy.  Apparently, the program's answers had been
>> |  "good enough" for the sub-orbital Mercury flights, so no one suspected
>> |  a bug until they tried to get greater accuracy, in anticipation of
>> |  later orbital and moon flights.  As far as I know, this particular bug
>> |  was never blamed for any actual failure of a space flight, but the
>> |  other details here seem close enough that I'm sure this incident is 
>> the
>> |  source of the DO story.

Fortran is an evil, evil language.


Sean