<P>Dear Kishore,</P>
<P>Sorry for troubled you so much, and I tried to modify my gs file again after the last email, and when I changed the command as next: </P>
<P> <FONT color="#ff0000">'define mpdsi=tloop(aave(maskout(pdsi,1),lon=61.25,lon=143.75,lat=-8.75,lat=56.25))' </FONT><FONT color="#ff0000"> </FONT></P>
<P><FONT color="#ff0000"><FONT color="#000000">it finally worked in opengrads without any error tips. so may I ask does it right about all my steps?</FONT></FONT></P>
<P>Thanks a lot! Best regards!</P>
<P>PS: I saw the last email didn't have the changed command, so I send it again here.</P>
<P>Zhihong<BR></P><SPAN></SPAN>
<P><SPAN></SPAN> </P>
<P><SPAN>--<BR></SPAN></P>
<P> Zhihong Zhuo,Postgraduate Student</P>
<P><FONT face="Times New Roman"> College of Environmental and Resource Sciences, Zhejiang University</FONT></P>
<P><FONT face="Times New Roman">Address: 866 Yuhangtan Road, Hangzhou, China</FONT></P>
<P><FONT face="Times New Roman">Email: <A href="mailto:fairyes@zju.edu.cn" target="_blank">fairyes@zju.edu.cn</A></FONT></P>
<P><FONT face="Times New Roman"></FONT> </P><BR><SPAN>--<BR>
<P> Zhihong Zhuo,Postgraduate Student</P>
<P><FONT face="Times New Roman"> College of Environmental and Resource Sciences, Zhejiang University</FONT></P>
<P><FONT face="Times New Roman">Address: 866 Yuhangtan Road, Hangzhou, China</FONT></P>
<P><FONT face="Times New Roman">Email: <A href="mailto:fairyes@zju.edu.cn" target="_blank">fairyes@zju.edu.cn</A></FONT></P>
<P><FONT face="Times New Roman"></FONT> </P></SPAN>