[gradsusr] If else in GRADS

[Mubashar Dogar]

Dear GrADS users,

Could you please help me to fix the following problem. I have a file
with one variable named NAO having different value for each year
(1980-2002). I have two other constant gridded fields A and B. My NAO
variable can have positive or negative values varying in between -3
and 3. I want to calculate a formula in such a way that I need its
values only when NAO absolute values are greater than 1. For other
values of NAO, I want that formula to have missing (NAN) values.

I am trying in the following way but it is not taking abs(NAO) instead
it is taking all the NAO values.


**********************************
Note: My A and B are constant gridded fields.
NAO is a varying means different value for each year and it is not gridded.
***********************************
Following is my script lines:

'set time jan1979 jan2001'
if ('abs(nao)' >= 1)
'define DT=B*nao+A'
else
'define DT=-999'
endif
'd DT'


I can use while and endwhile to tell each time individually but I
don't know why it is not considering absolute values of NAO.

Regards,

Mubashar