The Rice Distribution

Density, distribution function, quantile function and random generation for the Rician distribution.

drice(x, sigma, vee, log = FALSE)
price(q, sigma, vee, lower.tail = TRUE, log.p = FALSE, ...)
qrice(p, sigma, vee, lower.tail = TRUE, log.p = FALSE, ...)
rrice(n, sigma, vee)

Arguments

x, q

vector of quantiles.

p

vector of probabilities.

n

number of observations. Same as in runif.

vee, sigma

See riceff.

...

Other arguments such as lower.tail.

lower.tail, log.p

Same meaning as in pnorm or qnorm.

log

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

Value

drice gives the density, price gives the distribution function, qrice gives the quantile function, and rrice generates random deviates.

Author

T. W. Yee and Kai Huang

Details

See riceff, the VGAM family function for estimating the two parameters, for the formula of the probability density function and other details.

Formulas for price() and qrice() are based on the Marcum-Q function.

See also

riceff.

Examples

if (FALSE)  x <- seq(0.01, 7, len = 201)
plot(x, drice(x, vee = 0, sigma = 1), type = "n", las = 1,
     ylab = "",
     main = "Density of Rice distribution for various v values")
#> Error in h(simpleError(msg, call)): error in evaluating the argument 'x' in selecting a method for function 'plot': object 'x' not found
sigma <- 1; vee <- c(0, 0.5, 1, 2, 4)
for (ii in 1:length(vee))
  lines(x, drice(x, vee = vee[ii], sigma), col = ii)
#> Error: object 'x' not found
legend(x = 5, y = 0.6, legend = as.character(vee),
       col = 1:length(vee), lty = 1)
#> Error in (function (s, units = "user", cex = NULL, font = NULL, vfont = NULL,     ...) {    if (!is.null(vfont))         vfont <- c(typeface = pmatch(vfont[1L], Hershey$typeface),             fontindex = pmatch(vfont[2L], Hershey$fontindex))    .External.graphics(C_strWidth, as.graphicsAnnot(s), pmatch(units,         c("user", "figure", "inches")), cex, font, vfont, ...)})(dots[[1L]][[1L]], cex = dots[[2L]][[1L]], font = dots[[3L]][[1L]],     units = "user"): plot.new has not been called yet

x <- seq(0, 4, by = 0.01); vee <- 1; sigma <- 1
probs <- seq(0.05, 0.95, by = 0.05)
plot(x, drice(x, vee = vee, sigma = sigma), type = "l",
     main = "Blue is density, orange is CDF", col = "blue",
     ylim = c(0, 1), sub = "Red are 5, 10, ..., 95 percentiles",
     las = 1, ylab = "", cex.main = 0.9)
abline(h = 0:1, col = "black", lty = 2)
Q <- qrice(probs, sigma, vee = vee)
lines(Q, drice(qrice(probs, sigma, vee = vee),
               sigma, vee = vee), col = "red", lty = 3, type = "h")
lines(x, price(x, sigma, vee = vee), type = "l", col = "orange")
lines(Q, drice(Q, sigma, vee = vee), col = "red", lty = 3, type = "h")
lines(Q, price(Q, sigma, vee = vee), col = "red", lty = 3, type = "h")
abline(h = probs, col = "red", lty = 3)
max(abs(price(Q, sigma, vee = vee) - probs))  # Should be 0
#> [1] 1.221245e-14
 # \dontrun{}