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Name

tabcog - integrate a sorted table, using the Curve of Growth method

Synopsis

tabint [parameter=value]

Description

tabcog integrates a function Y=F(X) that is defined by a set of (X,Y) points selected from two columns from an ASCII table using a Curve of Growth (CoG) method (see Yu et al. 2020).

In this method the cumulative integral ("flux") is computed from a central point and the two are then added to compute the total integral. This central is automatically determines, but can be pre-set using the xc= keyword.

A novel way is using to determine the error in the integral, by using the RMS in the portion of the X-axis where there is no signal. See eq.(5) in Yu2020.

See also tabint(1NEMO) for a more traditional approach.

Parameters

The following parameters are recognized in order; they may be given in any order if the keyword is also given. Use --help to confirm this man page is up to date.
in=
Input table file.
No default.
xcol=
Column with sorted X coordinates. If the X coordinates are not increasing, the array will be reversed.
[Default: 1]
ycol=
Column with Y coordinate of the function
[Default: 2]

xc=
Center
By default it will be estimated automatically.

xmin=
If given, value below which data to be discarded
By default it uses the smallest datapoint from the table.
xmax=
If given, value above which data to be discarded
By default it uses the largest datapoint from the table.
tol=
Tolerance needed to reach the flat portion of the cumulative flux distribution.
[Default: 0.1]

Examples

Here we create a gaussian signal, and first integrate the numerically correct integral when no noise is added, after which some

noise is added and the CoG method is used to analyze the signal and compute

the flux and error in the flux

nemoinp 1000:2000:5 |\ tabmath - - ’exp(-(%1-1500)**2/(2*50**2))’ | tabint -
125.331

nemoinp 1000:2000:5 |\ tabmath - - ’exp(-(%1-1500)**2/(2*50**2))+rang(0,0.01)’ seed=123 |\
tabcog -
flux = 125.607 flux_std = 0.493996 vel = 1495.92 vel_std = 12.8628 A_F = 1.24842 A_C = 1.42753 C_V = 5.8 rms = 0.0107146 bchan = 60 echan = 138 width[0.25] = 25 +/- 5.00625 width[0.65] = 85 +/- 10.0361 width[0.75] = 115 +/- 5.13055 width[0.85] = 145 +/- 10.1046 width[0.95] = 195 +/- 5.3668

The flux should be ’sqrt(2*pi)*50’ = 125.331

See Also

tabint(1NEMO) , table(5NEMO)

https://ui.adsabs.harvard.edu/abs/2020ApJ...898..102Y/abstract

Ads

@ads

2020ApJ...898..102Y

Files

src/kernel/tab

Author

Peter Teuben

Update History


19-may-2026    V0.1 Cloned off tabint, aided by Claude    PJT

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