maxwell {VGAM} | R Documentation |
Estimating the parameter of the Maxwell distribution by maximum likelihood estimation.
maxwell(link = "loge", earg=list())
link |
Parameter link function applied to the parameter a.
See Links for more choices.
A log link is the default because the parameter is positive.
|
earg |
List. Extra argument for the link.
See earg in Links for general information.
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The Maxwell distribution, which is used in the area of thermodynamics, has a probability density function that can be written
f(y) = sqrt(2/pi) * a^(3/2) * y^2 * exp(-0.5*a*y^2)
for y>0 and a>0. The mean of Y is sqrt(8 / (a * pi)) (returned as the fitted values), and its variance is (3*pi - 8)/(pi*a).
An object of class "vglmff"
(see vglmff-class
).
The object is used by modelling functions such as vglm
,
rrvglm
and vgam
.
A related distribution is the Rayleigh distribution. Fisher-scoring and Newton-Raphson are the same here.
T. W. Yee
von Seggern, D. H. (1993) CRC Standard Curves and Surfaces, Boca Raton, FL.: CRC Press.
y = rmaxwell(n <- 1000, a=exp(2)) fit = vglm(y ~ 1, maxwell, trace=TRUE, crit="c") coef(fit, matrix=TRUE) Coef(fit)