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Extending VARTOOLS

VARTOOLS provides two extension mechanisms that let you add your own code without modifying the core source:

Extension type CLI flag What it adds
User Commands -L libname.so New pipeline commands (e.g., -mycommand …)
User Analytic Functions -F libname.so New functions for the expression evaluator (e.g., myfunc(t, mag))

Both are compiled as shared-object libraries that VARTOOLS loads at runtime. If the libraries are installed into the VARTOOLS data directory (make install handles this automatically), the full path to the .so file is not required.

User Commands (-L)

A user command library adds a new pipeline stage. It can read input parameters from the command line or the input list file, access the light curve arrays, compute results, store computed values, and output them in the standard VARTOOLS ASCII table.

Suitable for:

  • New period-search or model-fitting algorithms
  • Custom detrending or calibration steps
  • Anything that reads or modifies the light curve and/or produces scalar output

→ Writing User Extension Commands

User Analytic Functions (-F)

A user function library adds new functions to the VARTOOLS analytic expression evaluator. Functions take a fixed number of scalar arguments and return a scalar. They can be used anywhere an expression is accepted: -expr, "expr" keywords in command parameters, -Injectharm signal descriptions, etc.

Suitable for:

  • Custom window functions, apodisations, or signal shapes
  • Domain-specific transformations (e.g., limb-darkening laws, extinction curves)
  • Any pure mathematical function not already built into VARTOOLS

→ Writing User Analytic Functions

Bundled examples

Library Type Location What it does
magadd Command USERLIBS/src/magadd.c Add a constant to magnitudes — simplest possible command example
examplefunction Function USERFUNCS/src/examplefunction.c Adds addvals(a,b) — simplest possible function example
fastchi2 Command USERLIBS/src/fastchi2.c Palmer's Fast χ² periodogram (requires GSL)
jktebop Command USERLIBS/src/jktebop.c Detached eclipsing binary model (Fortran core)
macula Command USERLIBS/src/macula_c.c Kipping's analytic starspot model (Fortran 90 core)
stitch Command USERLIBS/src/stitch.c Zero-point offset removal for combined multi-telescope LCs
splinedetrend Command USERLIBS/src/splinedetrend.c Multivariate spline/polynomial detrending (requires GSL)
astrofuncs Function USERFUNCS/src/astrofuncs.c Astronomical utility functions