Estimates the two parameters of a Rice distribution by maximum likelihood estimation.
Logical. Suppress a warning? Ignored for VGAM 0.9-7 and higher.
Link functions for the v and sigma parameters.
Optional initial values for the parameters.
If convergence failure occurs (this VGAM family function seems
to require good initial values) try using these arguments.
The Rician distribution has density function
f(y;v,sigma) = (y/sigma^2) * exp(-(y^2+v^2) / (2*sigma^2)) * I_0(y*v/sigma^2)
where y > 0, v > 0, σ > 0 and I_0 is the modified Bessel function of the first kind with order zero. When v = 0 the Rice distribution reduces to a Rayleigh distribution. The mean is sigma*sqrt(pi/2) * exp(z/2)*((1-z) * I_0(-z/2)-z*I_1(-z/2)) (returned as the fitted values) where z=-v^2/(2*sigma^2). Simulated Fisher scoring is implemented.
An object of class
The object is used by modelling functions such as
Convergence problems may occur for data where v=0; if so, use
rayleigh or possibly use an
When v is large (greater than 3, say) then the mean is approximately v and the standard deviation is approximately sigma.
T. W. Yee
Rice, S. O. (1945). Mathematical Analysis of Random Noise. Bell System Technical Journal, 24, 46–156.
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