lgamma(1 + x) = log|Gamma(1 + x)|, accurate near x = 0 and x = 1, where it is near 0.
Not an R function. R has it only in its C API (Rmath.h), as lgamma1p.
Parameters
x: number
A number.
Returns number
log|Gamma(1 + x)|; Infinity at the poles (x a negative integer) and at x = Infinity, NaN for
x = -Infinity.
Example
lgamma1p(1e-10); // -5.7721566481928616e-11 (lgamma(1 + 1e-10) keeps only about 6 digits)
lgamma(1 + x) = log|Gamma(1 + x)|, accurate near x = 0 and x = 1, where it is near 0. Not an R function. R has it only in its C API (Rmath.h), as
lgamma1p.