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[fitsbits] How is NAXISn supposed to work?
ok, gently then. The crux is the (english) language I guess:
"index along axis 1 varies most rapid' ^^^^^^ ^^^^^ wihch refers to how an array DATA(i,j,k,....) is indexed. What they mean to say is that in a 2D example element DATA(i,j) is followed by DATA(i+1,j) [and not DATA(i,j+1)]. This is the fortran style of indexing, as opposed to the C style of indexing, where the last index varies most rapidly. If I reread the sentence, I'm not confused about the values of NAXISi, or that NAXIS1 NAXIS2.., but then again, I've been looking at, and using this type of data for some time. - peter On [Mon Apr 27 17:54], RPEHLM wrote: Hello folks, I'm a simple sort of chap, so I have a simple question! g Reading the IAUFWG v3 (2008 July 10) documentation for the Primary Data Array (page 14, section 3, sub 3.3.2). I'm not understanding what is meant by: "Arrays of more than one dimension shall consist of a sequence such that the index along axis 1 varies most rapidly, that along axis 2 next most rapidly, and those along subsequent axes progressively less rapidly, with that along axis m, where m is the value of NAXIS, varying least rapidly." Does axis 1 equate to NAXIS1 and axis 2 to NAXIS2 etc.? Should the value of NAXIS1 be greater than NAXIS2, which in turn should be greater than NAXIS3 etc.? Or should the value of NAXIS1 be the smallest and NAXISn the greatest? Or something else entirely? For example, take a 100 by 200 array, would the following be correct: NAXIS = 2 NAXIS1 = 100 NAXIS2 = 200 or this: NAXIS = 2 NAXIS1 = 200 NAXIS2 = 100 (Yes, I know the formatting is not exactly right g) The documentation would seem to indicate the former, but I have seen plenty of commercial applications implementing the later. Hence the confusion to my poor abused grey thing. Regards Robin P.S. My first posting so please be gentle!!! _______________________________________________ fitsbits mailing list http://listmgr.cv.nrao.edu/mailman/listinfo/fitsbits |
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