Module functions to display statistics as a function of parameter value, and to retrieve the value and statistic arrays
Struct_Type run_intunc(String_Type)
Struct_Type run_intproj(String_Type)
Argument:
(1) A string representing an individual thawed model parameter
These functions initiate the
INTERVAL-UNCERTAINTY and
INTERVAL-PROJECTION
parameter estimation methods respectively.
The chosen method is run using
the most recently fit datasets, which are automatically determined and
hence are not function arguments.
When done, each returns a structure,
which are the same as those returned by
get_intunc and
get_intproj.
These functions can be used to retrieve information similar to that
provided by the XSPEC command steppar.
Fit a dataset; get information about chi-square
as a function of power-law amplitude p.ampl
sherpa> () = load_dataset(1,"example.pha")
sherpa> () = set_subtract
sherpa> () = set_source_expr(1,"POW[p]")
sherpa> set_verbose(0)
sherpa> () = run_fit
sherpa> list_intproj()
Parameter Current Default Description
----------------------------------------------------------------------
fast 1 1 Switch to LM/simplex: 0(n)/1(y)
expfac 3 3 Expansion factor for grid
arange 1 1 Auto-range: 0(n)/1(y)
min 0 0 Minimum value
max 0 0 Maximum value
log 0 0 Log-spacing: 0(n)/1(y)
nloop 20 20 Number of grid points
sigma 1 1 Number of sigma
sherpa> sherpa.intproj.sigma = 3
sherpa> sherpa.intproj.nloop = 100
sherpa> intproj = run_intproj("p.ampl")
[...plot displayed...]
sherpa> print(intproj)
x0 = Float_Type[100]
y = Float_Type[100]
name = p.ampl
bfit = 0.000191983
config = sherpa_VisParEst_State
sherpa> printarr(intproj.x0,3)
9.19654e-05
9.39859e-05
9.60065e-05
sherpa> printarr(intproj.y,3)
270.566
267.213
263.936
The second-to-last call displays the first three values of
the p.ampl grid, while the last call displays
the best-fit statistic given those p.ampl values.
The run_intunc() and run_intproj() commands no longer fail with an error message when called. This means that you can use
retval = run_intproj(parameter_name); rather than having to use sherpa_eval() to call INTERVAL-PROJECTION (or INTERVAL-UNCERTAINTY) and then get_regproj() to access the results.
The structures returned by these functions contain additional fields: name, bfit, and config. These fields contain information on the name of the parameter, its best-fit value, and the values used by the "interval" command to calculate the x0 and y values.
These functions will only run after the dataset has been fitted; i.e run_fit() called in the same session. This is unlike the Sherpa versions of these commands, which have been updated in CIAO 3.2 to not require the inital fit.
See the Sherpa bug pages online for an up-to-date listing of known bugs.
- sherpa
-
berrors,
bsyserrors,
compute_errors,
compute_statistic,
covariance,
errors,
ftest,
get_paramest,
get_paramestint,
get_paramestlim,
get_paramestreg,
goodness,
interval-projection,
interval-uncertainty,
list_paramest,
mlr,
projection,
region-projection,
region-uncertainty,
restore_paramest,
run_paramest,
run_paramestlim,
run_paramestreg,
set_errors,
set_syserrors,
staterrors,
syserrors,
uncertainty
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