GreG stands for ``GREnoble Graphics'', this is the (free) program the graphic library of which is used in soas.
While you are using GreG, the prompt changes from ``
GreG>''. Type q after the GreG prompt to go back to soas.
You can use interactive GreG to do simple modifications of your buffer, such as adding a constant to the X data to change the potential scale, multiplying the Y data to normalize the current, etc...e.g.:
let y y|1.e-7'' if you want to normalise the current by the value 1.e-7 ; note that you've got to use ``
|'' instead of ``/'' to compute a ratio.
The list of elementary functions recognized by Greg is listed under
the heading "Functions and Operators" in the manual of
is the Natural logarithm,
LOG10 is the Decimal Logarithm.
When you modify the data in such a way, they are not re-plotted before you go back to soas (unless you type ``clear'' and return, ``limits'' and return, ``box'' and return and ``connect'' and return).
When you exit GreG (typing q and return), you are asked whether or not you want the new data to be passed to soas. If you answer yes, the current buffer is updated and plotted, if you answer no, your modifications are lost and the old data are re-plotted.
[Useless part : GreG defines three internal arrays, they are called X, Y and Z. soas' arrays x and y (potential and current) are transfered into X and Y while entering GreG. Updating the buffer when you go back to soas means putting X and Y back into x and y. You may as well use GreG's Z array (typing e.g. ``let Z 2*Y''). To transfer GreG's Z array into soas' y array exiting GreG, you may answer ``z'' to the question ``Update buffer ([y]/z/n) ?'' (answering ``y'' transfers Y into y and X into x, answering ``z'' puts Z into y and X into x, answering ``n'' does not update soas arrays).]
Greg manuals :
Christophe Leger 2009-02-24