POWGEN is a graphical interface program for displaying and manipulating powder diffraction pattern plots. It was designed to permit the user to dump an image of the manipulated page to a .ppp file for previewing with PREVUE or plotting with PLOTX. Multiple pages can be dumped and multiple powder plots can be displayed on one page. The graphical interface was designed exclusively using Tcl/Tk graphics functions, but if desired, the on screen graphics mode can be turned off and a complete description of ONE single page can be specified from the POWGEN control lines. That allows for efficient plotting once a plot format has been designed. In interactive mode the user can manipulate many of the attributes of either, the current graph block, or the layout of the whole page.

Figure 4.3. Screen shot of POWGEN

POWGEN requires as input, either of a .pat file produced by ADDPAT, or a .POT file produced by RIETVD. A check is made for the .POT file first, defaulting to the .PAT file if it exists. If the .PAT file is obtained, it is envisaged that a powder profile could be calculated and manipulated to a certain extent on screen. That requires atom site and hkl data on the input bdf so ADDATM and ADDREF are prerequisites in this mode. Many of the RIETVD commands also apply to POWGEN.

Page layouts can be either rigorously enforced to users specifications, or optimised to fit the page in a number of ways. The page layout is specified via the ARANGE option, where relative graph block positions are specified on a 9x9 grid, with (5,5) defining the location of a one graph block page. Typically EXAMPP will initiate with one graph invoked but with others being added or deleted as the user requires.