Calculates the contour level that encloses a given fraction of the data
in a multi-dimensional histogram.
Result = CONTOURLEVELS(Image, Enclosedfrac)
Image: A histogram in arbitrary dimensions, e.g. as generated
with HIST_2D or HIST_ND.
Enclosedfrac: The fraction of data points
Takes an IMAGE generated using something like HIST_2D, ie. which
contains the number of data points that fall within the bounds of
each pixel, and calculates the contour levels that enclose a given
fraction ENCLOSEDFRAC (which can be an array) of the data points.
The RESULT can be passed to CONTOUR as the LEVELS= argument.
IMAGE may have any dimensionality desired.
Note that this errs on the side of lower contour levels that enclose
a larger fraction of the data. I.e. if no contour level contains exactly
ENCLOSEDFRAC of the data points then RESULT will be the highest contour
level that contains no less than ENCLOSEDFRAC of the data.
Written by: Jeremy Bailin (lost in time..)