#
# = GSL::Histogram2d class
#
# == {}[link:index.html"name="1] Class methods
# ---
# * GSL::Histogram2d.alloc(nx, ny)
# * GSL::Histogram2d.alloc(xrange, yrange)
# * GSL::Histogram2d.alloc(nx, xmin, xmax, ny, ymin, ymax)
# * GSL::Histogram2d.alloc(nx, [xmin, xmax], ny, [ymin, ymax])
#
# Constructors.
#
# 1. With sizes
# >> h2 = GSL::Histogram2d.alloc(2, 3) # size 6
# >> h2.xrange
# => GSL::Histogram::Range:
# [ 0.000e+00 1.000e+00 2.000e+00 ]
# >> h2.yrange
# => GSL::Histogram::Range:
# [ 0.000e+00 1.000e+00 2.000e+00 3.000e+00 ]
# >> h2.bin
# => GSL::Histogram::Bin:
# [ 0.000e+00 0.000e+00 0.000e+00 0.000e+00 0.000e+00 0.000e+00 ]
# >> h2.xrange.class.superclass
# => GSL::Vector::View::ReadOnly
# >> h2.bin.class.superclass
# => GSL::Vector::View::ReadOnly
#
# 1. With ranges
# >> h2 = Histogram2d.alloc([3, 6, 7], [2, 3, 8])
# >> h2.xrange
# => GSL::Histogram::Range:
# [ 3.000e+00 6.000e+00 7.000e+00 ]
# >> h2.yrange
# => GSL::Histogram::Range:
# [ 2.000e+00 3.000e+00 8.000e+00 ]
# >> h2.bin
# => GSL::Histogram::Bin:
# [ 0.000e+00 0.000e+00 0.000e+00 0.000e+00 ]
#
# 1. With sizes and ranges
# >> h2 = Histogram2d.alloc(4, [0, 4], 3, [1, 5])
# >> h2.xrange
# => GSL::Histogram::Range:
# [ 0.000e+00 1.000e+00 2.000e+00 3.000e+00 4.000e+00 ]
# >> h2.yrange
# => GSL::Histogram::Range:
# [ 1.000e+00 2.333e+00 3.667e+00 5.000e+00 ]
#
# ---
# * GSL::Histogram2d.alloc_uniform(nx, xmin, xmax, ny, ymin, ymax)
# * GSL::Histogram2d.equal_bins_p(h1, h2)
#
#
# == {}[link:index.html"name="2] Methods
# ---
# * GSL::Histogram2d#set_ranges(vx, vy)
#
# This sets the ranges of the existing histogram using
# two {GSL::Vector}[link:files/rdoc/vector_rdoc.html] objects or arrays.
# ---
# * GSL::Histogram2d#set_ranges_uniform(xmin, xmax, ymin, ymax)
# * GSL::Histogram2d#set_ranges_uniform([xmin, xmax], [ymin, ymax])
#
# This sets the ranges of the existing histogram self to cover
# the ranges xmin to xmax and ymin to ymax uniformly.
# The values of the histogram bins are reset to zero.
#
# ---
# * GSL::Histogram2d#clone
# * GSL::Histogram2d#duplicate
#
# Returns a newly created histogram which is an exact copy of the
# histogram self.
#
# ---
# * GSL::Histogram2d#increment(x, y, weight = 1)
# * GSL::Histogram2d#accumulate(x, y, weight = 1)
# * GSL::Histogram2d#fill(x, y, weight = 1)
#
# These method update the histogram self by adding weight
# to the bin whose x and y ranges contain the coordinates (x,y).
# If (x,y) lies outside the limits of the histogram then none of the
# bins are modified.
#
# ---
# * GSL::Histogram2d#increment2(x, y, weight = 1)
# * GSL::Histogram2d#accumulate2(x, y, weight = 1)
# * GSL::Histogram2d#fill2(x, y, weight = 1)
#
# These are similar to GSL::Histogram#increment/accumulate/fill,
# but when (x,y) lies outside the limits of the histogram then the edge
# bin is incremented.
#
# ---
# * GSL::Histogram2d#get(i[, j])
# * GSL::Histogram2d#get([i, j])
# * GSL::Histogram2d#[i, j]
#
# Return the contents of the (i,j)-th bin of the histogram self.
#
# ---
# * GSL::Histogram2d#get_xrange(i)
# * GSL::Histogram2d#get_yrange(j)
#
# These methods find the upper and lower range limits of the i-th
# and j-th bins in the x and y directions of the histogram self.
#
# Ex:
# >> h2 = Histogram2d.alloc(2, [0, 2], 3, [1, 4])
# >> h2.get_xrange(1)
# => [1.0, 2.0]
# >> h2.get_yrange(1)
# => [2.0, 3.0]
#
# ---
# * GSL::Histogram2d#xrange
# * GSL::Histogram2d#yrange
#
# These methods returns the range of histogram as Vector::View objects.
#
# ---
# * GSL::Histogram2d#xmax
# * GSL::Histogram2d#xmin
# * GSL::Histogram2d#ymax
# * GSL::Histogram2d#ymin
# * GSL::Histogram2d#nx
# * GSL::Histogram2d#ny
#
# These methodss return the maximum upper and minimum lower range limits
# and the number of bins for the x and y directions of the histogram self.
#
# ---
# * GSL::Histogram2d#reset
#
# Resets all the bins of the histogram self to zero.
#
# ---
# * GSL::Histogram2d#find(x, y)
#
# Finds the indices i and j to the to the bin which covers the
# coordinates (x,y).
#
# ---
# * GSL::Histogram2d#max_val
#
# Returns the maximum value contained in the histogram bins.
#
# ---
# * GSL::Histogram2d#max_bin
#
# Returns the indices (i,j) of the bin containing the maximum value in
# the histogram self.
#
# ---
# * GSL::Histogram2d#min_val
#
# Returns the minimum value contained in the histogram bins.
# ---
# * GSL::Histogram2d#min_bin
#
# Returns the indices (i,j) of the bin containing the minimum value
# in the histogram self.
#
# ---
# * GSL::Histogram2d#xmean
#
# Returns the mean of the histogrammed x variable, where the histogram
# is regarded as a probability distribution.
# Negative bin values are ignored for the purposes of this calculation.
#
# ---
# * GSL::Histogram2d#xsigma
#
# Returns the standard deviation of the histogrammed x variable,
# where the histogram is regarded as a probability distribution.
# Negative bin values are ignored for the purposes of this calculation.
#
# ---
# * GSL::Histogram2d#ymean
#
# Returns the mean of the histogrammed y variable, where the histogram
# is regarded as a probability distribution. Negative bin values are
# ignored for the purposes of this calculation.
#
# ---
# * GSL::Histogram2d#ysigma
#
# Returns the standard deviation of the histogrammed y variable,
# where the histogram is regarded as a probability distribution.
# Negative bin values are ignored for the purposes of this calculation.
#
# ---
# * GSL::Histogram2d#cov
#
# Returns the covariance of the histogrammed x and y variables,
# where the histogram is regarded as a probability distribution.
# Negative bin values are ignored for the purposes of this calculation.
#
# ---
# * GSL::Histogram2d#sum
# * GSL::Histogram2d#integral
#
# Return the sum of all bin values. Negative bin values are included in the sum.
# ---
# * GSL::Histogram2d#add
# * GSL::Histogram2d#sub
# * GSL::Histogram2d#mul
# * GSL::Histogram2d#div
# * GSL::Histogram2d#scale(val)
# * GSL::Histogram2d#shift(val)
# * GSL::Histogram2d#fwrite(io)
# * GSL::Histogram2d#fwrite(filename)
# * GSL::Histogram2d#fread(io)
# * GSL::Histogram2d#fread(filename)
# * GSL::Histogram2d#fprintf(io, range_format, bin_format)
# * GSL::Histogram2d#fprintf(filename, range_format, bin_format)
# * GSL::Histogram2d#fscanf(io)
# * GSL::Histogram2d#fscanf(filename)
#
#
# ---
# * GSL::Histogram2d#xproject(jstart = 0, jend = ny-1)
#
# Creates a GSL::Histogram object by projecting the 2D histogram
# self onto the x-axis over the y-range from jstart to jend.
#
# ---
# * GSL::Histogram2d#yproject(istart = 0, iend = nx-1)
#
# Creates a GSL::Histogram object by projecting the 2D histogram
# self onto the y-axis over the x-range from istart to iend.
#
# == {}[link:index.html"name="3] GSL::Histogram2d::Pdf class
# ---
# * GSL::Histogram2d::Pdf.alloc(nx, ny)
#
# Constructors
#
# ---
# * GSL::Histogram2d::Pdf#init(h)
#
# Initializer with a GSL::Histogram2d object h.
#
# ---
# * GSL::Histogram2d::Pdf#sample(r1, r2)
#
#
# == {}[link:index.html"name="4] Example
# #!/usr/bin/env ruby
# require("gsl")
#
# N = 10000
# BINS = 100
#
# rng = Rng.new(2)
# h2 = Histogram2d.alloc(BINS, [-5, 5], BINS, [-8, 8])
#
# sig1 = 1.0
# sig2 = 2.0
#
# for i in 0...N do
# r1 = rng.gaussian(sig1)
# r2 = rng.gaussian(sig2)
# h2.increment(r1, r2)
# end
#
# hx = h2.xproject
# hy = h2.yproject
# printf("%f %f %f %f\n", h2.xsigma, h2.ysigma, hx.sigma, hy.sigma)
# GSL::graph(hx, hy, "-T X -C -g 3")
#
#
# {prev}[link:files/rdoc/hist_rdoc.html]
# {next}[link:files/rdoc/hist3d_rdoc.html]
#
# {Reference index}[link:files/rdoc/ref_rdoc.html]
# {top}[link:files/rdoc/index_rdoc.html]
#