ADJOIN-Append two spectra (strictly a merge by wavelength value)

Description:

ADJOIN is a Figaro routine whose primary function is to append one spectrum to another. That is, given two spectra, it produces one output spectrum where the X-axis and data arrays are formed by appending the second spectrum data onto the end of the data from the first.

In detail, ADJOIN is a little more complex, since it produces a spectrum in which the X data increase. This may involve the sorting of the various arrays, so ADJOIN can be regarded as a program that merges two spectra into increasing X order.

If neither spectrum has any X information (i.e. no wavelength array), the sort order will be first and then second. If one or both have X data, the resulting spectrum will be in order of X value.

Parameters:

SPECTRUM

SPECTRUM to be appended to.

SPECTRUM1

SPECTRUM1 specifies the second of the two spectra. Note that it is the structure of the first spectrum that is copied to the output spectrum. Only data arrays will be copied from the second.

OUTPUT

OUTPUT is the name of the resulting spectrum. Note that ADJOIN always produces a new file, even if OUTPUT has the same name as one of the input spectra. OUTPUT will have essentially the same structure as the first spectrum, but any array found in the X-axis or data structure of both input spectra, with the same length as the main data array in both spectra, will appear in OUTPUT as an array whose length is the sum of the two arrays.

Source comments:

 A D J O I N

 ADJOIN is a Figaro routine whose primary function is to
 append one spectrum to another.  That is, given two spectra,
 it produces one output spectrum where the .X and .Z arrays
 are formed by appending the second spectrum data onto the end
 of the data from the first.  In detail, ADJOIN is a little
 more complex, since it produces a spectrum in which the
 X data (the contents of the data object .X.DATA) increase.
 This may involve the sorting of the various arrays, so ADJOIN
 can be regarded as a program that merges two spectra into
 increasing X order. The resulting spectrum makes perfect
 sense if the data represent flux density measurements, but
 may be misleading if the data represent total flux measured
 within wavelength bins.  The X array may well not represent
 even a smooth wavelength vs channel relationship, let alone
 scrunched data.  Care should be taken in the use of this routine.

 Command parameters -

 SPECTRUM    (Character) The first of the two spectra.
 SPECTRUM1   (Character) The second of the two spectra.
 OUTPUT      (Character) The resulting output spectrum.

 Command keywords - None
                                            KS  / AAO 18th June 1985