Return the product \(f^2(x)(1-F(x))\).
pdfsqcdfstar(s,dist, p1,p2)
A scalar or vector: the x-axis grid points where the probability density function will be evaluated.
Character string, used as a switch to the user selected distribution function (see details below).
A scalar. Parameter 1 (vector or object) of the selected density.
A scalar. Parameter 2 (vector or object) of the selected density.
A vector containing the user selected density values at the user specified points s
.
Based on user-specified argument dist
, the function returns the value of
\(f^2(x)(1-F(x))dx\), used in the definitions of \(\rho_p^*\), \(\rho_p\) and their exact versions.
Supported distributions (along with the corresponding dist
values) are:
weib: The weibull distribution is implemented as $$f(s;p_1,p_2)= \frac{p_1}{p_2} \left (\frac{s}{p_2}\right )^{p_1-1} \exp \left \{- \left (\frac{s}{p_2}\right )^{p_1} \right \} $$ with \( s \ge 0\) where \(p_1\) is the shape parameter and \(p_2\) the scale parameter.
lognorm: The lognormal distribution is implemented as $$f(s) = \frac{1}{p_2s\sqrt{2\pi}}e^{-\frac{(log s -p_1)^2}{2p_2^2}}$$ where \(p_1\) is the mean and \(p_2\) is the standard deviation of the distirbution.
norm: The normal distribution is implemented as $$f(s) = \frac{1}{p_2\sqrt{2 \pi}}e^{-\frac{ (s - p_1)^2 }{ 2p_2^2 }}$$ where \(p_1\) is the mean and the \(p_2\) is the standard deviation of the distirbution.
uni: The uniform distribution is implemented as $$f(s) = \frac{1}{p_2-p_1}$$ for \( p_1 \le s \le p_2\).
cauchy: The cauchy distribution is implemented as $$f(s)=\frac{1}{\pi p_2 \left \{1+( \frac{s-p_1}{p_2})^2\right \} } $$ where \(p_1\) is the location parameter and \(p_2\) the scale parameter.
fnorm: The half normal distribution is implemented as $$2 f(s)-1$$ where $$f(s) = \frac{1}{sd\sqrt{2 \pi} }e^{-\frac{s^2}{2 sd^2 }},$$ and \(sd=\sqrt{\pi/2}/p_1\).
normmixt:The normal mixture distribution is implemented as
$$f(s)=p_1\frac{1}{p_2[2] \sqrt{2\pi} } e^{- \frac{ (s - p_2[1])^2}{2p_2[2]^2}} +(1-p_1)\frac{1}{p_2[4]\sqrt{2\pi}} e^{-\frac{(s - p_2[3])^2}{2p_2[4]^2 }} $$
where \(p1\) is a mixture component(scalar) and \(p_2\) a vector of parameters for the mean and variance of the two mixture components \(p_2= c(mean1, sd1, mean2, sd2)\).
skewnorm: The skew normal distribution with parameter \(p_1\) is implemented as $$f(s)=2\phi(s)\Phi(p_1s)$$.
fas: The Fernandez and Steel distribution is implemented as $$f(s; p_1, p_2) = \frac{2}{p_1+\frac{1}{p_1}} \left \{ f_t(s/p_1; p_2) I_{\{s \ge 0\}} + f_t(p_1s; p_2)I_{\{s<0 \}}\right \} $$ where \(f_t(x;\nu)\) is the p.d.f. of the \(t\) distribution with \(\nu = 5\) degrees of freedom. \(p_1\) controls the skewness of the distribution with values between \((0, +\infty)\) and \(p_2\) denotes the degrees of freedom.
shash: The Sinh-Arcsinh distribution is implemented as $$f(s;\mu, p_1, p_2, \tau) = \frac{ce^{-r^2/2}}{\sqrt{2\pi }} \frac{1}{p_2} \frac{1}{2} \sqrt{1+z^2} $$ where \(r=\sinh(\sinh(z)-(-p_1))\), \(c=\cosh(\sinh(z)-(-p_1))\) and \(z=((s-\mu)/p2)\). \(p_1\) is the vector of skewness, \(p_2\) is the scale parameter, \(\mu=0\) is the location parameter and \(\tau=1\) the kurtosis parameter.
# NOT RUN {
selected.dens <- "weib" #select Weibull
shape <- 2 # specify shape parameter
scale <- 1 # specify scale parameter
xout <- seq(0.1,5,length=50) #design point
pdfsqcdfstar(xout,selected.dens,shape,scale) #return f^2(xout)F(xout)
# }
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