External Utilities

(User Defined Functions (UDFs

undefine

free the resources used by the defined variable

set undef

This command allows the user to set the undefined data value for all forms of grads output. This command controls the undefined values printed to screen with the 'gxout stat' and the 'gxout print' output, as well as the undefined values in fwrite, sdfwrite, and geotiff files.  

query

The query command allows the user to get information about a variety of aspects of the current grads session. Configuration, plot characteristics, graphics specifics, and file structure are some examples. The use of query pos combined with the coordinate transformations is the basis of many interactive applications with buttons and drop menus. The query command may be shortened to simply q. The syntax is: