[gradsusr] SET A CONSTANT

[Stephen McMillan]

Arlindo,

I have found if_() is particularly useful when any part of the field is
undefined (-u), since if() will not work with undefined values.  That is
well documented in http://cola.gmu.edu/grads/gadoc/gradfuncif.html.

I will use if() when I can but will continue to use if_() when undefined is
involved, as is frequently the case.  Thanks for keeping that function in
opengrads.

Stephen Mc

where dt has values >= 0 along with missing values (-u)

So, it appears that undefined grid values must be changed to a "defined"
value representing an undefined value, before one can use the if function
on such fields.

Inter

On Wed, Mar 20, 2019 at 11:38 PM Arlindo da Silva <dasilva at alum.mit.edu>
wrote:

> On Fri, Mar 15, 2019 at 9:14 AM Stephen McMillan <
> smcmillan at planalytics.com> wrote:
>
>> Marian,
>> You are correct, regarding the "if" function in your version of
>> OpenGrADS.  The syntax I provided was for the latest (2.2.1) version.  In
>> the latest OpenGrADS version, you can either use "if" with the syntax as I
>> provided, or use "if_" with the syntax you provided.  Either way, you're
>> good to go!
>>
>>
> This is a subtle point. OpenGrADS has included an if() function for many
> years. Recently, COLA introduced an if() function, but unfortunately with a
> different syntax so it broke the code of people that had been using the
> OpenGrADS version. In 2.2.1 I renamed the OpenGrADS version if_() so they
> two can co-exist, although I strongly recommend that everyone migrate to
> the COLA version.
>
>    Arlindo
>
>
>
>
>
>> Best wishes--
>> Stephen
>>
>> On Thu, Mar 14, 2019 at 10:53 PM AMS EmsiWx Bytča <
>> emsiwx at pocasie-bytca.sk> wrote:
>>
>>> Once again thank you both guys, gave up const/maskout after sveral hours
>>> combining :D , used IF (did not know that it is already in 2.1.x version
>>> which I have), the correct syntax is:
>>>
>>>
>>> 'define A=if(tempdif,>,25,0,if(tempdif,>=,22,2,6))'
>>>
>>>
>>> Marian
>>>
>>>
>>>
>>> Dňa 14. 3. 2019 o 20:04 AMS EmsiWx Bytča napísal(a):
>>>
>>> Thank you Jeff and Stephen, will try to play with const/maskout first,
>>> then I will reinstall my Opengrads and try the if statement.
>>>
>>>
>>> Marian
>>> Dňa 14. 3. 2019 o 15:09 Stephen McMillan napísal(a):
>>>
>>> Marian,
>>>
>>> One correction to what I sent...
>>>
>>> 'define A=if(dt>25,0,if(dt>=22,2,6))'     added the second )
>>>
>>> Stephen
>>>
>>> On Thu, Mar 14, 2019 at 10:06 AM Stephen McMillan <
>>> smcmillan at planalytics.com> wrote:
>>>
>>>> Marian,
>>>>
>>>> If you have the latest version of GrADS or OpenGrADS, you could do
>>>> something like this:
>>>>
>>>> 'define dt=t850-t500'
>>>> 'define A=if(dt>25,0,if(dt>=22,2,6)'
>>>> 'd A'
>>>>
>>>> Stephen McMillan
>>>>
>>>> On Wed, Mar 13, 2019 at 4:14 PM AMS EmsiWx Bytča <
>>>> emsiwx at pocasie-bytca.sk> wrote:
>>>>
>>>>> Dear all,
>>>>>
>>>>>
>>>>> I am going crazy combining const/maskout to get what I need.
>>>>>
>>>>> I need to set A according the following:
>>>>>
>>>>> A= 0 when T850-T500 >25
>>>>>
>>>>> A= 2 when T850-T500 22-25
>>>>>
>>>>> A= 6 when T850-T500 <22
>>>>>
>>>>>
>>>>> Would like to ask any master of const/maskout for help.
>>>>>
>>>>>
>>>>> Thank you very much in advance.
>>>>>
>>>>>
>>>>> Marian
>>>>>
>>>>> _______________________________________________
>>>>> gradsusr mailing list
>>>>> gradsusr at gradsusr.org
>>>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>>>
>>>>
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>
>
> --
> Arlindo da Silva
> *dasilva at alum.mit.edu <dasilva at alum.mit.edu>*
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