/*  demhist2.aml
/*  aml to make a histogram of a DEM
/*  to be run from GRID
/*     Ralph Haugerud, USGS Seattle
/*     April 1998
/*       rhaugerud@usgs.gov

&arg ingrid CI CU

&if [null %CU%] &then &do
  &type USAGE: &r DEMHIST2 <DEM> <CI> <CU>
  &type where CI = contour interval of source map, in source-map Z units
  &type   and CU = contour units of source map, in InGrid Z units
  &type (typically InGrid is in meters and contour units are feet, 
  &type  so CU = 1/3.2808 = .3048)
  &return
  &end
  
&s offset = [round [calc 0.5 * %CI%]]
/* offset = 1/2 contour interval

NG1 = %InGrid% / (%CU%) + %offset%
%ingrid%h2 = INT(NG1 MOD %CI%) - %offset%
/* statements above calculate grid of vertical distances 
/* from  nearest contour
kill NG1 all

histogram %ingrid%h2

&return