conversion


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#######################################################################
#   f2c
#   convert evil Fahrenheit to Celcius
#   SJP     April 2007
f2c <- function(deg, sc='F', string=FALSE){
#   sc == scale (default is f therefore cvt tfrom F to C)
  sc <- substr(toupper(sc),1,1)       # clean input
	if (sc=='F'){
	    res <- (deg - 32) * (5/9)
	    to <- 'C'
	} else {
	    res <- deg * 1.8 + 32
	    to <- 'F'; sc <- 'C'
	}
	if (string) res <- sprintf('Converted from %i %1s to %i %1s.', 
						round(deg, 0), sc, round(res, 0), to)
	return(res)
}

###########  Exponential growth functions #############################

#######################################################################
#   convert growth rate ('interest rate' version) to doubling time
dblTime <- function(x) {
	return(log(2)/log(1 + x))
}
#######################################################################
#	convert doubling time to 'interest rate'
intRate <- function(x) {
	return((exp(log(2)/x))-1)
}