Re: [netcdfgroup] how to change a missing value

• To: "ryofurue@xxxxxxxxx" <ryofurue@xxxxxxxxx>
• Subject: Re: [netcdfgroup] how to change a missing value
• From: Nick Humphries <clockworktent@xxxxx>
• Date: Tue, 22 Apr 2025 05:41:43 +0000
• Feedback-id: 48792839:user:proton

Hi,

Well, NetCDF specifies default fill values for all data types, so the most 
compliant solution is to one of those. Although I realise that this comment is 
off post.

Cheers,

Nick.

Please consider email bloat when replying to this email ;-)

Sent from Proton Mail Android

-------- Original Message --------
On 22/04/2025 04:15, Ryo Furue  wrote:

> Chris,
>
>>> Having said that, NaN is usually "safer" in that its use causes error, 
>>> making your bugs easier to spot.
>>
>> agreed, I like NaN as a fill value, but there's a downside -- NaN dpes not 
>> equal NaN, so code that does:
>>
>> if something == fill_value:
>>
>> Will not work. It can be tricky.
>
> That's exactly the reason for the "isnan()" function:
>
>> if (isnan(fill_value)) . . .
>
> The Fortran language also includes such a function as part of its language 
> standard:
>
>> use:: ieee_arithmetic
>>
>> if (ieee_is_nan(fill_value)) then
>> . . .
>
> In addition, Fortran compilers tend to include a compile option to enable 
> "floating-point exception traps". If you enable the "invalid value" trap at 
> the compile time, at the runtime, the program stops with an error message as 
> soon as a NaN is generated or operated upon. This sometimes helps debug your 
> code.
>
> Ryo

• References:
  • [netcdfgroup] how to change a missing value
    • From: Cathy Smith
  • Re: [netcdfgroup] how to change a missing value
    • From: Ryo Furue
  • Re: [netcdfgroup] how to change a missing value
    • From: Chris Barker
  • Re: [netcdfgroup] how to change a missing value
    • From: Ryo Furue