Keywords: greg

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### Using Variables

Instead of reading data into the X, Y, Z or Regular Grid buffers, it is possible to use directly SIC variables in some GREG commands. Currently, the following commands support SIC variables as extra arguments :

          GREG1\CONNECT [Xv Yv]
          GREG1\CURVE [Xv Yv] [/VARIABLE Z [Zv]]
          GREG1\HISTOGRAM [Xv Yv]
          GREG1\ERRORBAR Type [Xv Yv Zv [Orv]]
          GREG1\POINTS [Xv Yv] [/SIZE maxsize [Zv]]
          GREG1\VALUES [Xv Yv Zv]

where, if not specified, the Xv Yv Zv variables default to the X Y Z buffers, which are known as SIC variables of the same names.

SIC variables are defined using command `SICDEFINE`, and can be external tables or images. See SIC documentation, or use `HELP DEFINE` within GREG for more details.

The option `/VARIABLE` of command `RGDATA` indicates that the argument is the name of a known SIC variable, instead of a file name. This can be used to contour directly 2-D SIC variables. Moreover, the Regular Grid is known as a SIC variable named RG, hence it is possible to assign values to RG within GREG . This does not modify the pixel to user coordinates conversion formula.