[gradsusr] SET error: Missing or invalid arguments

[Dr. Muhammad Afzaal]

Dear Fellows

I am trying to calculate linear trend (Grads V2.0.1 on ubuntu 13);

'sdfopen Era_RH_1981.nc'
'set t 1 last'
'ltrend r rh slope error' ;*r is the input variable

But got the error;

SET error:  Missing or invalid arguments for X option
SET error:  Missing or invalid arguments for Y option
SET error:  Missing or invalid arguments for T option
Syntax Error:  Invalid dimension expression
  Dimension value missing or invalid
Error from SUM:  1st dimension expression invalid
Operation Error:  Error from sum function
Operation Error:  Error from tloop function
  Error ocurred at column 1
.............
.............

Tried many options but could not resolve. Can anybody help me solve this
problem

Following is file info;

   dimensions:
      longitude = 55
      latitude = 43
      time = 360  // unlimited
   variables:
      float longitude ( longitude )
         standard_name :        longitude
         long_name :    longitude
         units :        degrees_east
         axis : X

      float latitude ( latitude )
         standard_name :        latitude
         long_name :    latitude
         units :        degrees_north
         axis : Y

      double time ( time )
         standard_name :        time
         units :        hours since 1900-01-01 00:00:00
         calendar :     standard

      float r ( time, latitude, longitude )
         standard_name :        relative_humidity
         long_name :    Relative humidity
         units :        %
         _FillValue :   -32767


Thanking in anticipation

*Dr. MUHAMMAD AFZAAL *
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