free grads

set hershey

set hershey on | off

This command, which is available beginning with grads version 2.1, is a quick shortcut for users who would like to take advantage of Cairo fonts but do not know anything about font files on their system or do not want to bother editing the font controls in existing scripts. Invoking 'set hershey off' will tell grads to use generic Cairo fonts that are reasonable approximations of Hershey fonts 0, 1, 2, 4, and 5. Font 3 is the Greek (symbol) font, and cannot be duplicated with generic controls. 'set hershey on' will return grads to the use of traditional Hershey fonts.  

set hempref

set hempref auto|nhem|shem

This command controls the way wind barbs are plotted for any output where wind barbs are produced (e.g. set gxout barb). The options are as follows: 

hdivg

(hdivg(uexpr,vexpr

Calculates the horizontal divergence using finite differencing. Exactly the same as hcurl in all other respects; see the Usage Notes and Examples above. 

Reading NetCDF and HDF Files with grads

Data files in the NetCDF and HDF file formats are called self-describing files (SDF) because the data and metadata are packaged together in the same file. grads can read data NetCDF and HDF formatted files, as long as the data are on a regular grid. The HDF format is very general; the grads interface is limited to gridded data sets that fit into the internal 5-D lon/lat/lev/time/ensemble grid space. grads handles HDF4 Scientific Data Sets and (as of version 2.0.a7) some HDF5 files. In order to read the data in SDFs, grads needs a certain amount of metadata in order to place the data in the internal grid space. There are three ways to do this:

(hcurl(uexpr,vexpr

Calculates the vertical component of the curl (ie, vorticity) at each grid point using finite differencing on the grids provided. It is assumed that uexpr gives the U Wind component, and that vexpr provides the V Wind component.

Producing Hardcopy and Image Output from grads

grads version 2.1 introduced the use of the Cairo library to handle all the graphics rendering, both for the interactive display in X windows and for the hardcopy and image outputs. The addition of Cairo means that grads can support drawing a wide variety of fonts, smoother looking anti-aliased lines, transparent colors, pattern filling, and more options for graphical output formats. These features provide an opportunity to create some beautifully polished publication-quality graphics.