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Re: Recognizing double precision? [message #56235 is a reply to message #56164]

Wed, 10 October 2007 08:53

R.G.Stockwell
Messages: 163
Registered: October 2004

Senior Member

<meinel@aero.org> wrote in message
news:1192025265.336346.261400@o3g2000hsb.googlegroups.com...
> On Oct 9, 11:50 am, "R.G. Stockwell" <noem...@please.com> wrote:
>> "wlandsman" <wlands...@gmail.com> wrote in message
>>
>> news:1191597160.614557.153160@50g2000hsm.googlegroups.com...
>>
>>> About once a year I receive a complaint about my code because someone
>>> inputs a Julian date like this
>>
>>> IDL> jd = 2441636.1
>>
>> btw, this may be obvious to all, but you can force the input
>> with a read command, read it as string, and cast it to double.
>>
>> IDL> .GO
>>
>> : 2441636.1
>>
>> S STRING = ' 2441636.1'
>>
>> 2441636.1
>>
>> single:
>>
>> 2441636.00000
>>
>> double
>>
>> 2441636.10000
>>
>> Cheers,
>> bob
>
> Sure, you _could_ do that, but that is even worse than
>
> IDL>jd = 2441636.1d

Not worse, just different. The problem is that we are talking about
different things. One is a user interface, in which the developer should
be responsible for inputting the correct variable type. (thus, read string,
and then do error checking, range checking, valid input checking and casting
to the appropriate type). Because one thing is certain, if a user _can_
do something that will crash the code, then the user _will_do something
to crash the code (I've even run into malicious users who try to crash
the code so they can stop working.)

The second, above, is input at the IDL command line. That is, in my
opinion, identical to a line of code in a program. If the developer types in
jd = 2441636.1
in their routine when they should have made it a double, then that is a
programming error.
It is entirely the programmers responsibility to have the correct type for
their variables.

I don't think the compiler should take the defined floating point variable
and force it to double unless the programmer tells it to (either explicitly
or implicitly). Just my opinion anyway.

Cheers,
bob

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[Message index]

		Recognizing double precision? By: wlandsman on Fri, 05 October 2007 08:12
		Re: Recognizing double precision? By: edward.s.meinel@aero. on Wed, 10 October 2007 11:21
		Re: Recognizing double precision? By: R.G.Stockwell on Wed, 10 October 2007 08:53
		Re: Recognizing double precision? By: edward.s.meinel@aero. on Wed, 10 October 2007 07:07
		Re: Recognizing double precision? By: R.G.Stockwell on Tue, 09 October 2007 08:50
		Re: Recognizing double precision? By: Maarten[1] on Tue, 09 October 2007 08:24
		Re: Recognizing double precision? By: edward.s.meinel@aero. on Tue, 09 October 2007 08:11
		Re: Recognizing double precision? By: R.Bauer on Wed, 24 October 2007 11:15

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