.help subsets May85 noao.imred.iids/noao.imred.irs
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NAME
subsets - Subtract pairs of spectra in a string
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USAGE
subsets input records
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PARAMETERS
.ls input
The root file name for the input spectra in the string.
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.ls records
The range of spectra indicating the elements of the string.
The names of the spectra will be formed by appending the range
elements to the input root name.
.le
.ls output
This is the root file name for the names of the spectra which will
be created by the subtraction operation.
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.ls start_rec
The starting record number to be appended to the root name of the
created spectra.
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DESCRIPTION
Pairs of spectra are formed from the input string in the order that
the record numbers would suggest. 
The first spectrum in the pair is assumed to be the
principle spectrum and the second spectrum in the pair is subtracted
from the first. The result is written out as a new spectrum.

No compensation is made for exposure time during the subtraction.
The header from the principle spectrum is assigned to the output
spectrum.

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EXAMPLES
The following example forms 50 new spectra from nite1.2001-nite1.2002,
nite1.2003-nite1.2004, ...

	cl> subsets nite1 2001-2100

The following example creates new spectra from the pairs nite2.2001-nite2.2002,
nite2.2003-nite2.2004 in spite of the order of the record numbers entered.

	cl> subsets nite2 2001,2003,2002,2004
.endhelp
