pbvnorm: Probabilities for Bivariate Normal Distribution

In pbv: Probabilities for Bivariate Normal Distribution

Description

The function pbvnorm computes probabilities Φ_2(x,y,ρ) for the standardized bivariate normal distribution (Drezner & Wesolowsky, 1990; West, 2004).

The function dbvnorm computes the corresponding density φ_2(x,y,ρ).

Usage

pbvnorm(x, y, rho)

dbvnorm(x, y, rho, log=FALSE)

## exported Rcpp functions
pbv_rcpp_pbvnorm0( h1, hk, r)
pbv_rcpp_pbvnorm( x, y, rho)
pbv_rcpp_dbvnorm0( x, y, rho, use_log)
pbv_rcpp_dbvnorm( x, y, rho, use_log)

Arguments

x	Vector of first ordinate
y	Vector of second ordinate
rho	Vector of correlations
log	Logical indicating whether logarithm of the density should be calculated
h1	Numeric
hk	Numeric
r	Numeric
use_log	Logical

Value

A vector

Note

The pbv package can also be used to include Rcpp functions for computing bivariate probabilities at the C++ level. Numeric and vector versions are

double pbv::pbv_rcpp_pbvnorm0( double h1, double hk, double r)

Rcpp::NumericVector pbv::pbv_rcpp_pbvnorm( Rcpp::NumericVector x,
Rcpp::NumericVector y, Rcpp::NumericVector rho)

References

Drezner, Z., & Wesolowsky, G. O. (1990). On the computation of the bivariate normal integral. Journal of Statistical Computation and Simulation, 35(1-2), 101-107. doi: 10.1080/00949659008811236

Genz, A. (1992). Numerical computation of multivariate normal probabilities. Journal of Computational and Graphical Statistics, 1(2), 141-149.

West, G. (2005). Better approximations to cumulative normal functions. Wilmott Magazine, 9, 70-76.

See Also

See pbivnorm::pbivnorm in the pbivnorm package and mnormt::biv.nt.prob in the mnormt package for alternative implementations (Genz, 1992).

Examples

#############################################################################
# EXAMPLE 1: Comparison with alternative implementations
#############################################################################

#*** simulate different values of ordinates and correlations
set.seed(9898)
N <- 3000
x <- stats::runif(N,-3,3)
y <- stats::runif(N,-3,3)
rho <- stats::runif(N,-.95,.95)

#*** compute probabilities
res1 <- pbv::pbvnorm(x=x,y=y,rho=rho)

#-- compare results with pbivnorm package
library(pbivnorm)
res2 <- pbivnorm::pbivnorm(x=x, y=y, rho=rho)

summary(abs(res1-res2))

#*** compute density values
log <- TRUE    # logical indicating whether log density should be evaluated
res1 <- pbv::dbvnorm(x=x, y=y, rho=rho, log=log )

## Not run: 
#-- compare results with mvtnorm package
library(mvtnorm)
res2 <- rep(NA, N)
sigma <- diag(2)
for (ii in 1:N){
    sigma[1,2] <- sigma[2,1] <- rho[ii]
    res2[ii] <- mvtnorm::dmvnorm(x=c(x[ii],y[ii]), sigma=sigma, log=log)
}
summary(abs(res1-res2))

## End(Not run)

Example output

     Min.   1st Qu.    Median      Mean   3rd Qu.      Max. 
0.000e+00 7.500e-12 6.020e-11 3.312e-09 5.083e-10 3.534e-07 
     Min.   1st Qu.    Median      Mean   3rd Qu.      Max. 
1.421e-14 2.931e-14 2.931e-14 2.965e-14 3.020e-14 5.684e-14 

pbv documentation built on July 1, 2020, 7:04 p.m.