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Ten Eyck MAP Format Files

Ten Eyck map files are unformatted files. They are used to store various density maps. The file begins with a variable number of comment records 80 characters long. All comment records begin with an asterisk (``*") except for the last comment record.

After the comments follow one or more map sections, each composed of two records. The first record of a map section contains eight integer numbers. The first is the grid value for this section. The next two give the starting and ending grid value in grid points along the fast direction, then the next two numbers give the range in the slow direction. The last three numbers give the sampling rate along each axis (fast first, then slow, and finally section).

The second record contains (FAST<end> - FAST<start> + 1)*
(SLOW<end> - SLOW<start> + 1)\

real numbers which is the map section. The End of File is detected when the header record for a section contains only -1's. There will be no records following this header record.

There is a standard convention for which axes are ``fast'', ``slow'', and ``section''. When the map file contains Z sections, X is fast and Y is slow. For Y sections, Z is fast and X is slow. It rarely arises but when X sections are desired Y is fast and Z is slow. In general the preference is for Z sections. Ideally any program which reads Ten Eyck map files should accept any type of sectioning, but this ideal is rarely achieved.

Dale Edwin Tronrud
Thu Jul 6 23:24:57 PDT 2000