link
- sherpa.astro.ui.link(par, val)
Link a parameter to a value.
A parameter can be linked to another parameter value, or function of that value, rather than be an independent value. As the linked-to values change, the parameter value will change.
Changed in version 4.16.1: Source models no longer have to contain the linked parameter.
- Parameters:
See also
Notes
The
link
attribute of the parameter is set to match the mathematical expression used forval
.In the following, the fit will vary the
pos
parameter even though thesrc2
component is not part of the source expression (this behavior changed in the 4.16.1 release):>>> set_source(1, gauss1d.src1) >>> gauss1d.src2 >>> link(src1.pos, src2.pos) >>> fit(1)
The
lpars
attribute of a source model will include these “extra” parameters:>>> get_source(1).lpars (<Parameter 'pos' of model 'src2'>,)
Examples
The
fwhm
parameter of theg2
model is set to be the same as thefwhm
parameter of theg1
model.>>> link(g2.fwhm, g1.fwhm)
Fix the
pos
parameter ofg2
to be 2.3 more than thepos
parameter of theg1
model.>>> gauss1d.g1 >>> gauss1d.g2 >>> g1.pos = 12.2 >>> link(g2.pos, g1.pos + 2.3) >>> g2.pos.val 14.5 >>> g1.pos = 12.1 >>> g2.pos.val 14.399999999999999