[gradsusr] Fill and missing value

[Partha S Bhattacharjee]

Hi,

 How to account for missing and fill value in a GrADS .ctl file ? I am trying to read MIROC5 data using GrADS and data have 1.0E20 as missing and fill value. 

My .ctl file looks like this : 

 DSET   ^pr_Amon_MIROC5_historical_r1i1p1_185001-
201212.nc
options template
UNDEF  1.0E20 _FillValue
TITLE  MIROC5 Monthly Precipitation
XDEF  256 LINEAR   0.0 1.406
YDEF  128 LINEAR  -88.92 1.4
ZDEF  1 LEVELS 1
TDEF  1956 LINEAR 00Z01JAN1850 1mon
VARS 1
pr    1.0E-16 0 kg m-2 s-1
ENDVARS

and I am trying to plot (global, monthly) using this command : 

define pra = const(const(maskout(pr,pr-1.0E20),1),0,-u)

 And it does not plot anything. Please let me know, where it is going wrong ?

 Partha