Two new functions in common.R

Celsius2Kelvin()
Kelvin2Celsius()

Including very crude error checks (checks that supplied temperature
is not below absolute zero, if so, sets it to absolute zero).
Idea: would be nice if function returned same number of significant
digits as it received.
master
Taha Ahmed 14 years ago
parent 0f6eebe463
commit 5a5f3133d3

@ -1,7 +1,78 @@
# common.R
# General-purpose functions
# Taha Ahmed, Jan 2011
# CONTENTS
# >>>> Celsius2Kelvin
# >>>> Kelvin2Celsius
# >>>> as.radians
# >>>> as.degrees
# >>>> molarity2mass
##################################################
############### Celsius2Kelvin ###################
##################################################
Celsius2Kelvin <- function(Celsius) {
# Converts temperature from Celsius to Kelvin
#
# Check and correct for values below -273.15
if (Celsius < -273.15) {
# If Celsis is less than absolute zero, set it to absolute zero
Celsius <- -273.15
}
Kelvin <- Celsius + 273.15
}
##################################################
############### Kelvin2Celsius ###################
##################################################
Kelvin2Celsius <- function(Kelvin) {
# Converts temperature from Kelvin to Celsius
#
# Check and correct for negative values
if (Kelvin < 0) {
# If Kelvin is less than zero, set it to zero
Kelvin <- 0
}
Celsius <- Kelvin - 273.15
}
##################################################
################# as.radians #####################
##################################################
as.radians <- function(degrees) {
# Converts from degrees to radians
radians <- degrees * (pi / 180)
}
##################################################
################# as.degrees #####################
##################################################
as.degrees <- function(radians) {
# Converts from radians to degrees
radians <- radians * (180 / pi)
}
##################################################
############### molarity2mass ####################
##################################################
molarity2mass <- function(formulamass, volume, molarity) {
# Calculates the required mass of
# the substance to be dissolved.
# ARGS: formulamass - formula mass of the substance (in gram per mole)
# volume - volume of the final solution (in liters)
# molarity - molarity (in moles per liter)
# VALUE: mass of substance (in grams)
#
mass <- formulamass * volume * molarity
# Unit check:
# [g * mol-1] * [liter] * [mole * liter-1] = [g]
return(mass)
}

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