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.\" RCSid "$Id: histo.1,v 1.3 2003/12/14 16:33:37 greg Exp $"
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.TH HISTO 1 9/6/96 RADIANCE
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.SH NAME
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histo - compute 1-dimensional histogram of N data columns
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.SH SYNOPSIS
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.B "histo [-c][-p] xmin xmax nbins"
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.br
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.B "histo [-c][-p] imin imax"
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.SH DESCRIPTION
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.I Histo
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bins columnular data on the standard input between the given minimum
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and maximum values.
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If three command line arguments are given, the third is taken as the
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number of data bins between the first two real numbers.
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If only two arguments are given, they are both assumed to be integers,
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and the number of data bins will be equal to their difference plus one.
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The bins are always of equal size.
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.PP
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The output is N+1 columns of data (for N columns input), where the
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first column is the centroid of each division, and each row
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corresponds to the frequencies for each column around that value.
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.PP
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If the
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.I \-c
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option is present, then
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.I histo
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computes the cumulative histogram for each column instead of the
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straight frequencies.
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The upper value of each bin is printed also instead of the centroid.
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This may be useful in computing percentiles, for example.
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Values below the minimum specified are still counted in the cumulative
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total.
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.PP
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The
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.I \-p
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option tells
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.I histo
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to report the percentage of the total number of input lines rather
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than the absolute counts
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In the case of a cumulative total, this yeilds the percentile values
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directly.
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Values above the maximum are counted as well as values below in
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this case.
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.PP
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All input data is interpreted as real values, and columns must be
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white-space separated.
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If any value is less than the minimum or greater than the maximum,
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it will be ignored unless the
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.I \-c
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option is specified.
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.SH EXAMPLE
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To count data values between -1 and 1 in 50 bins:
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.IP "" .2i
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histo -1 1 50 < input.dat
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.PP
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To count frequencies of integers between 0 and 255:
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.IP "" .2i
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histo 0 255 < input.dat
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.SH AUTHOR
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Greg Ward
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.SH "SEE ALSO"
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cnt(1), neaten(1), rcalc(1), rlam(1), tabfunc(1), total(1)
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