# 3. calculations

The IntCal package also provides some functions related to radiocarbon calibration. First there are two functions to calculate radiocarbon ages from pMC values (in this case of a postbomb date):

    pMC.age(150, 1)

    ## [1] -3257    53

and the other way round:

    age.pMC(-2300, 40)

    ## [1] 133.000   0.661

We can also obtain the calibrated probability distributions from radiocarbon dates, e.g. one of 130 +- 20 C14 BP:

    calib.130 <- caldist(130, 20, BCAD=TRUE)
    plot(calib.130, type="l")

For reporting purposes, calibrated dates are often reduced to their 95% highest posterior density (hpd) ranges (please report all, not just your favourite one!):

    hpd(calib.130)

    ##      from   to perc
    ## [1,] 1683 1738 24.4
    ## [2,] 1755 1761  1.8
    ## [3,] 1801 1938 68.6

Want a plot of the radiocarbon and calibrated dates, together with their hpd ranges?

    calibrate(130,20)

You can also draw one or more calibrated distributions:

    set.seed(123)
    dates <- sort(runif(5, 100, 1000))
    errors <- .05*dates
    depths <- 0:4
    labels <- c("my", "very", "own", "simulated", "dates")
    draw.dates(dates, errors, depths, BCAD=TRUE, labels=labels, cal.lim=range(dates, 600, 1700))

or add them to an existing plot:

    plot(0, type="n", xlim=c(600, 1700), ylim=c(5,-1), xlab="AD", ylab="dates")
    draw.dates(dates, errors, depths, BCAD=TRUE, add=TRUE, labels=labels)

<- prev (plots)