statmod (version 1.3.3)

logmdigamma: Log Minus Digamma Function

Description

The difference between the log and digamma functions.

Usage

logmdigamma(x)

Arguments

x
numeric vector or array of positive values. Negative or zero values will return NA.

Details

digamma(x) is asymptotically equivalent to log(x). logmdigamma(x) computes log(x) - digamma(x) without subtractive cancellation for large x.

References

Abramowitz, M., and Stegun, I. A. (1970). Handbook of mathematical functions. Dover, New York.

See Also

digamma

Examples

Run this code
log(10^15) - digamma(10^15) # returns 0
logmdigamma(10^15) # returns value correct to 15 figures

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