attribute, pixel_type
Return details of the min,max or absolute max flux in a map.
EXAMPLE
-------
1. Display the min,max and absolute max flux in the current map.

 0>pr peak(flux,min),peak(flux,max),peak(flux,abs)
 -0.543233 3.44326 3.44326 
 0>

2. Shift the phase-center to that of the map pixel that contains the
   max absolute flux to the center of the map.

 0>shift -peak(x),-peak(y)
 shift: Shifting UV data, clean models and windows by: 20 (mas) East
 shift: Shifting UV data, clean models and windows by: -20 (mas) North
 0>

PARAMETERS
----------
attribute  -  The name of the attribute of the selected pixel to be
              returned by the function.
              Possible values are:
               flux -  The flux of the selected pixel.
               x    -  The X-axis position of the pixel.
               y    -  The Y-axis position of the pixel.

pixel_type -  Default = abs
              The name of the type of pixel to return the details of.
              Possible values are:
               abs  -  The pixel with the max absolute flux in the map.
               min  -  The pixel with the min flux in the map.
               max  -  The pixel with the max flux in the map.

CONTEXT
-------
peak() is a function that returns details about one of two specific
pixels of the current residual or clean map. The two pixels are, the
pixel having the mininum flux in the map, and the pixel having the
maximum flux in the map. In addition, one of these pixels has a higher
abolute flux than the other, and requesting the pixel with the max
absolute flux will return details about this pixel.

The selectable attributes of the requested pixel are its (signed)
flux, and its X and Y axis positions with respect to the center of the
map, all measured in map units.

SIDE EFFECTS
------------
If the map is not up to date, then it will be inverted before a value
is returned.

RELATED FUNCTIONS
-----------------
mapvalue - Return the value of the map pixel closest to a given position.
imstat  - Return image plane map statistics.
