constants: Update to 2018 CODATA values
This article is originally published at https://www.enchufa2.es
The constants package contains CODATA internationally recommended values of the fundamental physical constants, provided as symbols for direct use within the R language. Optionally, the values with uncertainties and/or units are also provided if the errors, units and/or quantities packages are installed. The Committee on Data for Science and Technology (CODATA) is an interdisciplinary committee of the International Council for Science which periodically provides the internationally accepted set of values of the fundamental physical constants. This release contains the “2018 CODATA” version, published on May 2019 [E. Tiesinga, P. J. Mohr, D. B. Newell, and B. N. Taylor (2020) http://physics.nist.gov/constants].
This version contains some breaking changes that are necessary to streamline future updates and provide a stable symbol table:
- The
codata
table includes the absolute uncertainty instead of the relative one. Thus, therel_uncertainty
column has been dropped in favour of the newuncertainty
. Also, columns have been slightly reordered. - Symbol names for constants have changed. The old ones were hand-crafted and thus unmanageable. This release adopts the ASCII symbols defined by NIST in their webpage, except for those that collide with some base R function. In particular, there are two cases:
c
, the speed of light, has been renamed asc0
;sigma
, the Stefan-Boltzmann constant, has been renamed assigma0
. - Constant types, or categories, (column
codata$type
) adopts the names defined by NIST in the webpage too. Some constants belong to more than one category (separated by comma); some others belong to no category (missing type).
There are some new features too:
- In addition to the
codata
data frame, this release includescodata.cor
, a correlation matrix for all the constants. - In addition to
syms_with_errors
andsyms_with_units
, there is a new list of symbols calledsyms_with_quantities
(available if the optionalquantities
package is installed), which provides constant values with uncertainty and units. - Experimental support for correlated values in
syms_with_errors
andsyms_with_quantities
is provided (disabled by default; see details inhelp(syms)
for activation instructions).
See the README for some usage examples. For questions, suggestions or issues, please use the issue tracker.
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This article is originally published at https://www.enchufa2.es
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