logcf {DPQ} | R Documentation |
Compute a continued fraction approximation to the series (infinite sum)
sum(k=0,...,Inf; x^k/(i+k*d)) = 1/i + x/(i+d) + x^2/(i+2*d) + x^3/(i+3*d) + ...
Needed as auxiliary function in log1pmx()
and lgamma1p()
.
logcf(x, i, d, eps, maxit = 10000)
x |
numeric vector |
i |
positive numeric |
d |
non-negative numeric |
eps |
positive number, the convergence tolerance. |
maxit |
a positive integer, the maximal number of iterations or terms in the truncated series used. |
a numeric vector with the same attributes as x
.
Rescaling is done by (namespace hidden) “global”
scalefactor
....
Martin Maechler, based on ....
lgamma1p
, log1pmx
, and
pbeta
, whose prinicipal algorithm has evolved from TOMS 708.
l32 <- curve(logcf(x, 3,2, eps=1e-7), -3, 1) abline(h=0,v=1, lty=3, col="gray50") plot(y~x, l32, log="y", type = "o", main = "logcf(*, 3,2) in log-scale")