HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.

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addcomp

add component to a model

Add a component to the model.

Syntax: addcomp [<modeName>:]<n> <comp>

where <n> is the component number before which the new component is to be inserted, and <comp> is the name of the new component. Components are numbered in sequence in order of appearance in the expression entered. The new component is regarded as an operator on the component added if it is not additive.

The optional <modelName> qualifier allows the user to address a named model.

The user is prompted for parameter values for the component. If there are m components in the current model, then acceptable values for the component number added are 1 to m+1.

XSPEC detects the type of the model (additive, multiplicative etc), checks the correctness of the syntax of the output model, and adds the component if the resulting models obeys the syntax rules documented in the model command.

Thus, 

XSPEC12> mo  wa(po)
Followed by 
XSPEC12> addcomp 2 bb
Yields the model achieved by 
XSPEC12> mo  wa(bb + po)
See also delcomp (delete component by number).

Other examples will serve to clarify addcomp's behavior. Suppose that the current model specification is 

ga+po
which using the show command would yield the description 
model  = gaussian[1] + powerlaw[2]
The comments give the model expression following the entry of addcomp and delcomp commands: 

XSPEC12> addcomp 2 wab 
// gaussian[1] + wabs[2](powerlaw[3])
XSPEC12> addcomp 4 pha 
// (gaussian[1] + wabs[2](powerlaw[3]))phabs[4]
XSPEC12> delcomp 1	
// (wabs[1](powerlaw[2]))phabs[3]}
XSPEC12> addcomp 2 zg 
// (wabs[1](zgauss[2] + powerlaw[3]))phabs[4]
XSPEC12> delcomp 3 
// (wabs[1](zgauss[2]))phabs[3]

XSPEC12> mo wa(po)
XSPEC12> addcomp 1 ga
// gauss[1] + wabs[2]*powerlaw[3]
XSPEC12> delcomp 1
XSPEC12> addcomp 1 pha
// phabs[1]*wabs[2]*powerlaw[3]

XSPEC12>mo wabs(po)
XSPEC12> addcomp 3 bb
// wabs[1]*powerlaw[2] + bbody[3]
XSPEC12> delcomp 1
XSPEC12> addcomp 3 pha
// wabs[1]*powerlaw[2]*pha[3]
XSPEC12> addcomp 3 po
// ERROR: po (additive) is interpreted as being added to the 
// multiplicative model pha[3], which is a context error.

For multiply nested models?
XSPEC12> mo wa(po + pha(bb + ga))
XSPEC12> addcomp 6 po
// wabs[1](powerlaw[2] + phabs[3](bbody[4] + ga[5]) + powerlaw[6])
XSPEC12> addcomp 5 peg
// wabs[1](powerlaw[2] + phabs[3](bbody[4] + pegpwlw[5] ga[6]) + powerlaw[7])
XSPEC12> addcomp 7 wa
// wabs[1](powerlaw[2] + phabs[3](bbody[4] + pegpwlw[5] ga[6]) + wabs[7]*powerlaw[8])
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Last modified: Friday, 23-Aug-2024 13:20:40 EDT

HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.