| log {base} | R Documentation |
log computes natural logarithms,
log10 computes common (i.e., base 10) logarithms, and
log2 computes binary (i.e., base 2) logarithms.
The general form logb(x, base) computes logarithms with base
base.
log1p(x) computes log(1+x) accurately also for
|x| << 1 (and less accurately when x is approximately -1).
exp computes the exponential function.
expm1(x) computes exp(x) - 1 accurately also for
|x| << 1.
log(x, base = exp(1)) logb(x, base = exp(1)) log10(x) log2(x) exp(x) expm1(x) log1p(x)
x |
a numeric or complex vector. |
base |
positive number. The base with respect to which
logarithms are computed. Defaults to e=exp(1). |
exp and log are generic functions: methods can be defined
for them individually or via the Math
group generic.
log10 and log2 are only special cases, but will be computed
more efficiently and accurately where supported by the OS.
A vector of the same length as x containing the transformed
values. log(0) gives -Inf (when available).
log and logb are the same thing in R, but logb
is preferred if base is specified, for S-PLUS compatibility.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
The New S Language.
Wadsworth & Brooks/Cole.
(for log, \log10 and exp.)
Chambers, J. M. (1998)
Programming with Data. A Guide to the S Language.
Springer. (for logb.)
Trig,
sqrt,
Arithmetic.
log(exp(3)) log10(1e7)# = 7 x <- 10^-(1+2*1:9) cbind(x, log(1+x), log1p(x), exp(x)-1, expm1(x))