Precession constant implied by an observed obliquity or precession cycle

Usage

cycles_to_k(period_kyr, term = "k+s3", g = NULL, s = NULL, data_dir = NULL)

period_kyr: Period of the cycle read from the record, in kyr (numeric, > 0; can be a vector of several readings of the same term), i.e. from a tuned record or a known sedimentation rate. Required, no default.
term: Astronomical term the cycle represents (character): "k+s3" (obliquity) or one of the precession terms "k+g5", "k+g2", "k+g4", "k+g3" (aliases such as "obl" and "prec" are accepted, see astro_terms); a term without k (an eccentricity term) gives an error. Default="k+s3".
g: Secular frequencies g1 to g9 in arcsec/yr (numeric vector of length 9) used instead of the La2004 values; NULL uses the La2004 values from La04gisi.csv. Default=NULL.
s: Secular frequencies s1 to s9 in arcsec/yr (numeric vector of length 9) used instead of the La2004 values; NULL uses the La2004 values from La04gisi.csv. Default=NULL.
data_dir: Folder that contains the astronomical data tables AstroGeo22.txt and La04gisi.csv (character path); NULL uses the tables installed with the package (or the folder set with options(cocoR.data = ...)). Default=NULL.

list: p in arcsec/yr and the precession constant k in years