Program:       AXSWAP

Purpose:       Swap first and second axis of 2-dim (sub) set
               and/or change the sign of the grid separation.

Category:      MANIPULATION, HEADER

File:          axswap.c

Author:        M.G.R. Vogelaar

Keywords:

   INSET=      Give set and (2-dim) subsets:
               Maximum number of subsets is 2048.


   OUTSET=     Give output set (, subsets):
               Output set and subset(s) for the result. The number of
               output subsets is the same as the number of input sub-
               sets.

   SWAPAXES=   Swap x and y axis?                               [Y]/N
               If you answer with No, then you can still change
               the sign of the pixel separations with keywords
               CHSEPX= and CHSEPY=

   CHSEPX=     Change sign of NEW pixel separation in x:         Y/[N]
               If Y then the grid ranges in x will be changed
               so that physical positions are unaltered.

   CHSEPY=     Change sign of NEW pixel separation in y:         Y/[N]
               If Y then the grid ranges in y will be changed
               so that physical positions are unaltered.


Description:   The order of data is changed according to the following
               table:
               SWAPAXES  CHSEPX  CHSEPY   xnew:   ynew:
                   Y       N       N        y       x
                   Y       Y       N       -y       x
                   Y       N       Y        y      -x
                   Y       Y       Y       -y      -x
                   N       N       N        x       y
                   N       Y       N       -x       y
                   N       N       Y        x      -y
                   N       Y       Y       -x      -y


Notes:         All header items on set level and subset level will be
               stored in the output, but items on levels that intersect
               these subsets will be lost in the transformation.

Example:

Updates:       Jan 12,  1993: VOG, Document created.
               Sep 19,  1995: VOG, Added keywords SWAPAXES=, CHSEPX= and
                                   CHSEPY=
               Nov 25,  2010: VOG, Removed bug with changing deltas while
                                   not swapping axes.