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Last modified: December 2013

URL: http://cxc.harvard.edu/sherpa/ahelp/polynomial.html
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AHELP for CIAO 4.9 Sherpa v1

polynomial

Context: models

Synopsis

1-D polynomial function of order <= 5

Description

A 1-D polynomial of order <= 5, taking the functional form:

f(x) = sum_(i=0)^5 c_i (x-x_off)^i ,

where the coefficients c_i are the parameters numbered i+1, and x_off is parameter number 7.

Note that there is a degeneracy in the parameters, so it is recommended to set at least one of c_0 or x_off to zero and freeze it; thawing both may lead to unpredicted results.

Note also that all coefficients except c_0 are default frozen, so that the default polynomial model is a constant.

Parameters

Number Name Description
1 c0 coefficient c_0
2 c1 coefficient c_1
3 c2 coefficient c_2
4 c3 coefficient c_3
5 c4 coefficient c_4
6 c5 coefficient c_5
7 offset offset for x x_off

Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

models
absorptionedge, absorptiongaussian, absorptionlorentz, absorptionvoigt, accretiondisk, atten, bbody, bbodyfreq, beta1d, beta2d, blackbody, box1d, box2d, bpl1d, bremsstrahlung, brokenpowerlaw, ccm, const1d, const2d, cos, delta1d, delta2d, dered, devaucouleurs2d, disk2d, edge, emissiongaussian, emissionlorentz, emissionvoigt, erf, erfc, exp, exp10, fm, gauss1d, gauss2d, hubblereynolds, jdpileup, linebroad, list_model_components, list_models, lmc, load_xscflux, load_xsgsmooth, load_xsireflect, load_xskdblur, load_xskdblur2, load_xskerrconv, load_xslsmooth, load_xspartcov, load_xsrdblur, load_xsreflect, load_xssimpl, load_xszashift, load_xszmshift, log, log10, logabsorption, logemission, logparabola, lorentz1d, lorentz2d, models, normbeta1d, normgauss1d, normgauss2d, opticalgaussian, poisson, polynom1d, polynom2d, powerlaw, powlaw1d, recombination, scale1d, scale2d, schechter, seaton, sersic2d, shell2d, sigmagauss2d, sin, sm, smc, sqrt, stephi1d, steplo1d, tablemodel, tan, xgal, xs, xsabsori, xsacisabs, xsagauss, xsapec, xsbapec, xsbbody, xsbbodyrad, xsbexrav, xsbexriv, xsbkn2pow, xsbknpower, xsbmc, xsbremss, xsbvapec, xsbvvapec, xsc6mekl, xsc6pmekl, xsc6pvmkl, xsc6vmekl, xscabs, xscemekl, xscevmkl, xscflow, xscompbb, xscompls, xscompmag, xscompps, xscompst, xscomptb, xscompth, xscomptt, xsconstant, xsconvolve, xscplinear, xscutoffpl, xscyclabs, xsdisk, xsdiskbb, xsdiskir, xsdiskline, xsdiskm, xsdisko, xsdiskpbb, xsdiskpn, xsdust, xsedge, xseplogpar, xseqpair, xseqtherm, xsequil, xsexpabs, xsexpdec, xsexpfac, xsezdiskbb, xsgabs, xsgadem, xsgaussian, xsgnei, xsgrad, xsgrbm, xsheilin, xshighecut, xshrefl, xskerrbb, xskerrd, xskerrdisk, xslaor, xslaor2, xslogpar, xslorentz, xslyman, xsmeka, xsmekal, xsmkcflow, xsnei, xsnotch, xsnpshock, xsnsa, xsnsagrav, xsnsatmos, xsnsmax, xsnsmaxg, xsnsx, xsnteea, xsnthcomp, xsoptxagn, xsoptxagnf, xspcfabs, xspegpwrlw, xspexmon, xspexrav, xspexriv, xsphabs, xsplabs, xsplcabs, xsposm, xspowerlaw, xspshock, xspwab, xsraymond, xsredden, xsredge, xsrefsch, xsrnei, xssedov, xssirf, xssmedge, xsspexpcut, xsspline, xssrcut, xssresc, xssss_ice, xsstep, xsswind1, xstbabs, xstbgrain, xstbvarabs, xsuvred, xsvapec, xsvarabs, xsvbremss, xsvequil, xsvgadem, xsvgnei, xsvmcflow, xsvmeka, xsvmekal, xsvnei, xsvnpshock, xsvphabs, xsvpshock, xsvraymond, xsvrnei, xsvsedov, xsvvapec, xsvvgnei, xsvvnei, xsvvnpshock, xsvvpshock, xsvvrnei, xsvvsedov, xswabs, xswndabs, xsxion, xszagauss, xszbabs, xszbbody, xszbremss, xszdust, xszedge, xszgauss, xszhighect, xszigm, xszpcfabs, xszphabs, xszpowerlw, xszredden, xszsmdust, xsztbabs, xszvarabs, xszvfeabs, xszvphabs, xszwabs, xszwndabs, xszxipcf

Last modified: December 2013
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