NAME

fstatistic -- Compute statistics (min, max, mean, etc..) for a given column in a FITS ASCII or binary table file extension.

USAGE

        fstatistic infile[ext#] colname 

DESCRIPTION

This task computes the mean, standard deviation, minimum, and maximum of the data in the specified column. The rows included in the calculation can be specified. Maximum and minimum values can be specified, outside of which the data will not be included in the calculation. If either the maximum and/or the minimum requested is equal to INDEF, it will not be tested for. The output is written to STDOUT and to the parameter file by default. The output may also be directed to a file.

Note that in the case of vector columns, statistics are computed on the *sum* of the vector elements in each row of the table (i.e. the reported mean value is that of all the individual sums in each row). For alternate vector column handling, please use the ftstat task which computes statistics for the total number of elements, in all of the rows of each column.

PARAMETERS

infile [filename]

The name of the FITS file (including extension number in square brackets) of the input FITS table.

colname [string]

Name of the column in the input table. The statistics are calculated for this column. If the column is multi-dimensional, the statistics are based on the sum of all elements of the column. The statistics on a specific element of the vector/array can be requested by specifying the element: COLNAME(10,4) or COLNAME[30;4].

rows [string]

String containing the requested rows to include in the calculation. If the value is "-", the entire file will be used.

(outfile=STDOUT) [filename]

Optional output file name to write the statistics. If preceeded by a !, an existing file of the same name will be overwritten.

(maxval=INDEF) [real]

The maximum value to include in the calculation. A value of INDEF indicates that no upper limit will be used in the calculation.

(minval=INDEF) [real]

The minimum value to include in the calculation. A value of INDEF indicates no lower limit.

(sum= ) [real]

Value of the sum of the specified column is returned to this parameter.

(mean= ) [real]

Value of the mean of the specified column is returned to this parameter.

(sigma= ) [real]

The value of the standard deviation is written to this parameter.

(min= ) [real]

The minimum value in the requested column is written into this parameter.

(max= ) [real]

The maximum value in the requested column is written to this parameter.

(numb= ) [integer]

The number of values actually used in the calculation is returned.

(clobber=no) [boolean]

If true, an existing file of the same name as the requested output file will be overwritten.

EXAMPLES

1. Compute the statistics for the 'FLUX' column in the second extension in the input FITS file named 'myfile.fits':

         ft> fstatistic myfile.fits[2] flux

SEE ALSO

ftstat, ftlist

CATEGORY