skewnorm {VGAM}

Skew-Normal Distribution

Description

Density and random generation for the univariate skew-normal distribution.

Usage

dskewnorm(x, location = 0, scale = 1, shape = 0, log = FALSE)
rskewnorm(n, location = 0, scale = 1, shape = 0)

Arguments

x

vector of quantiles.

n

number of observations. Same as runif.

location

The location parameter \xi. A vector.

scale

The scale parameter \omega. A positive vector.

shape

The shape parameter. It is called \alpha in skewnormal.

log

Logical. If log=TRUE then the logarithm of the density is returned.

Details

See skewnormal, which currently only estimates the shape parameter. More generally here, Z = \xi + \omega Y where Y has a standard skew-normal distribution (see skewnormal), \xi is the location parameter and \omega is the scale parameter.

Value

dskewnorm gives the density, rskewnorm generates random deviates.

Note

The default values of all three parameters corresponds to the skew-normal being the standard normal distribution.

Author(s)

T. W. Yee

References

http://tango.stat.unipd.it/SN.

See Also

skewnormal.

Examples

## Not run:  N <- 200  # Grid resolution
shape <- 7; x <- seq(-4, 4, len = N)
plot(x, dskewnorm(x, shape = shape), type = "l", col = "blue", las = 1,
     ylab = "", lty = 1, lwd = 2)
abline(v = 0, h = 0, col = "grey")
lines(x, dnorm(x), col = "orange", lty = 2, lwd = 2)
legend("topleft", leg = c(paste("Blue = dskewnorm(x, ", shape,")", sep = ""),
       "Orange = standard normal density"), lty = 1:2, lwd = 2,
       col = c("blue", "orange")) 
## End(Not run)