next up previous contents index
Next: Using Variables Up: Two-Dimensional Regular Grid Array Previous: Variables and Images:   Contents   Index

RGDATA File Format :

A somewhat obsolete way of initializing the RGDATA array is rge so-called ``RGDATA file format''. Suitably formatted files can be read by the RGDATA command when no /VARIABLE option is specified. A header is read first to find the array dimensions, and then the array, using a user-specified format. The default format is Z8.8 and can be changed using the /FORMAT Expression option. . Expression must be a valid FORTRAN format. It is possible to select only a subset of the input array, using the option /SUBSET IX1 IY1 IX2 IY2, where IX1 and IY1 are the pixel values of the bottom left corner, IX2 IY2 those of the top right corner of the area to be selected.

The input file for the RG buffer must be a fixed length formatted sequential file with 80-Bytes record length. The first four records are used to describe the correspondence between indices and User Coordinates and must give the following values

All the following records contain the RG array, written in the standard Fortran ordering (I varies first) in format 20A4. The variables XREF, XVAL, XINC, YREF, YVAL and YINC are declared Real*8 to provide accurate conversion formulae. The conversion formulae are thus
         X(I) = XINC*(I-XREF)+XVAL
         Y(J) = YINC*(J-YREF)+YVAL
respectively for X and Y coordinates.


next up previous contents index
Next: Using Variables Up: Two-Dimensional Regular Grid Array Previous: Variables and Images:   Contents   Index
Gildas manager 2020-12-02