Fast 2D histogram calculation

Hist2D performs a fast calculation of 2D histograms. On a 2GHz processor, calculated and displayed a histogram of 1 million points in less than half a second.

HIST2D 2D histogram

[H XBINS YBINS] = HIST2D(D, XN, YN, [XLO XHI], [YLO YHI])
[H XBINS YBINS] = HIST2D(D, 'display' ...)

HIST2D calculates a 2-dimensional histogram and returns the histogram array and (optionally) the bins used to calculate the histogram.

Inputs:
D: N x 2 real array containing N data points or N x 1 array of N complex values
XN: number of bins in the x dimension (defaults to 20)
YN: number of bins in the y dimension (defaults to 20)
[XLO XHI]: range for the bins in the x dimension (defaults to the minimum and maximum of the data points)
[YLO YHI]: range for the bins in the y dimension (defaults to the minimum and maximum of the data points)
'display': displays the 2D histogram as a surf plot in the current axes

Outputs:
H: 2D histogram array (rows represent X, columns represent Y)
XBINS: the X bin edges (see below)
YBINS: the Y bin edges (see below)

As with histc, h(i,j) is the number of data points (dx,dy) where x(i) <= dx < x(i+1) and y(j) <= dx < y(j+1). The last x bin counts values where dx exactly equals the last x bin value, and the last y bin counts values where dy exactly equals the last y bin value.

If D is a complex array, HIST2D splits the complex numbers into real (x) and imaginary (y) components.