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math::constants(n) 1.0.1 tcllib_1_13 "Tcl Math Library"


math::constants - Mathematical and numerical constants

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  • package require Tcl ?8.3?
  • package require math::constants ?1.0.1?


This package defines some common mathematical and numerical constants. By using the package you get consistent values for numbers like pi and ln(10).

It defines two commands:

The motivation for this package is that quite often, with (mathematical) computations, you need a good approximation to, say, the ratio of degrees to radians. You can, of course, define this like:

    variable radtodeg [expr {180.0/(4.0*atan(1.0))}]

and use the variable radtodeg whenever you need the conversion.

This has two drawbacks:

Here is the way you can do it with the math::constants package:

    package require math::constants
    ::math::constants::constants radtodeg degtorad

which creates two variables, radtodeg and (its reciprocal) degtorad in the calling namespace.

Constants that have been defined (their values are mostly taken from mathematical tables with more precision than usually can be handled) include:


The package defines the following public procedures:

::math::constants::constants args

Import the constants whose names are given as arguments

::math::constants::print-constants args

Print the constants whose names are given as arguments on the screen (name, value and description) or, if no arguments are given, print all defined constants. This is mainly a convenience procedure.


This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category math :: constants of the Tcllib SF Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.


constants, degrees, e, math, pi, radians