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##

Function: `statistics()`

0
`void statistics(float *input, int n, int num_bins)`

This function calculates and displays the mean
value, standard deviation, signal-to-noise ratio, and confidence
intervals for an input array
of (assumed) statistically independent measurements of a
random variable .
This function also write output data to two files:
`histogram.dat` and `gaussian.dat`.
The first file contains a histogram of the input data ;
the second file contains the Gaussian probability distribution
that best matches this histogram.
(See Sec. for more details.)

The arguments of `statistics()` are:

`input:` Input.
`input[0..n-1]` is an array of floating point variables containing
the values of a set of (assumed) statistically independent measurements
of a random variable .
`n:` Input.
The length of the input data array.
If , `statistics()` prints out an error message and aborts
execution.
`num_bins:` Input.
The number of bins to be used when constructing a histogram of the
input data .

`statistics()` calculates and displays the mean
value and standard deviation of the input data .
It also calculates and displays the signal-to-noise ratio and 68%, 90%,
and 95% confidence intervals for the input data, assuming that the
are statistically independent measurements of a random variable .
`statistics()` also writes output data to two files:

- (i)
`histogram.dat` is a two-column file of floating point numbers
containing a histogram of the input data .
The length of each column of data is equal to `num_bins`, and
the histogram is normalized so that it has unit area.
- (ii)
`gaussian.dat` is a two-column file of floating point numbers
containing the Gaussian probability distribution function that best
matches the histogram of the input data .
Each column of `gaussian.dat` has a length equal to 8192.
There are also three *markers* included in the Gaussian
probability distribution data:
One marker for the mean, and two for the one standard deviation
values of .

- Authors:
Bruce Allen, ballen@dirac.phys.uwm.edu, and Joseph Romano, romano@csd.uwm.edu
- Comments:
In the context of the stochastic background routines,
`statistics()` is used to perform a statistical analysis of
the cross-correlation signal values calculated by the
function `analyze()`.

** Next:** Example: simulation program
** Up:** GRASP Routines: Stochastic background
** Previous:** Function: prelim_stats()
** Contents**
Bruce Allen
2000-11-19