AnalyzeO2 <- function (o2) {
# This code is written for the R language.  http://www.R-Project.org
# 
# This function calculates the Working Depth (imperial or feet) for  
# a particular oxygen partial pressure in a scuba cylinder.
# Calculations are based on the PADI/DSAT equations.
#
# The first section prints out the range of Working Depths for the 
# scuba tank along with hypoxia warnings.  This includes the Maximum 
# Working Depth and the Contingent Working Depth.
#
# The second section prints out in table format, the conversion from
# actual depth to Equvalent Air Depth (EAD) and the associated PO2 for
# use with the Recreational Dive Planner.
#
# Author: Stephen Quashnick
# Date: 20060120
# Version: 20060120-02
#
# USAGE: AnalyzeO2(0.21) 
# Enter partial pressure of O2 as a decimal i.e. 0.21
#
# This section determine the Working Depth for the O2 mix.
#
options(digits=3)
o2 <- (trunc(o2*100))/100 # Truncates extra digits for safety and leaves only two digit decimal number.
maxdepth <- as.double(format(((1.4/o2)-1)*33, digits=getOption("digits")))
mindepth <- as.double(format(((0.16/o2)-1)*33, digits=getOption("digits")))
maxcontingentdepth <- as.double(format(((1.6/o2)-1)*33, digits=getOption("digits")))
mincontingentdepth <- as.double(format(((0.12/o2)-1)*33, digits=getOption("digits")))
if (mindepth > -0.001) {
cat("EANx",o2*100," is hypoxic above ",mindepth,"fsw!\n", sep="")
}
if (mincontingentdepth > -0.001) {
cat("EANx",o2*100," above ",mincontingentdepth,"fsw may result in unconciousness!\n", sep="")
}
if (mindepth < 0.001) {
mindepth <- c(0)
}
if (mincontingentdepth < 0.001) {
mincontingentdepth <- c(0)
}
cat("\nThe Working Depth range for EANx",o2*100," is ",mindepth," to ",maxdepth," fsw.\n", sep="")
cat("The Contigent Working Depth range for EANx",o2*100," is ",mincontingentdepth," to ",maxcontingentdepth," fsw.\n\n", sep="")
#
# Print Depth, EAD and PO2 in Chart format
#
Depth <- seq(mincontingentdepth, maxcontingentdepth, by=10)
PO2 <- (trunc(as.double(format(c(((Depth+33)/33)*o2), digits=getOption("digits")))*100))/100
EAD <- trunc(as.double(format(c((((1-o2)/0.79)*(Depth+33))-33), digits=getOption("digits"))))
Line <- c(2:length(Depth))
cat("     \tEAD @\n", sep="")
cat("Depth\tEANx",o2*100,"\tPO2\n", sep="")
cat("(fsw)\t(fsw)\t(ata)\n", sep="")
for (i in Line) {
if (EAD[i] < 0 ) {
EAD[i] <- c(0)
}
cat(Depth[i],"\t",EAD[i],"\t",PO2[i],"\n", sep="")
}
}