Diff command in ROOT?

Hi, all:

In Paw, we have “diff” command. Please see below. I would like to know what’s the corresponding command in ROOT? Does anyone know? Thanks in advance!!



    ID1 C 'First Histogram Identifier’
    ID2 C 'Second Histogram Identifier’
    CHOPT C ‘Options’ D=‘D’

    Possible CHOPT values are:

    ’ ’ The comparison is done only on the shape of the two histograms.
    N Include also comparison of the relative normalisation of the two
    histograms, in addition to comparing the shapes. PROB is then a
    combined confidence level taking account of absolute contents.
    D Debug printout, produces a blank line and two lines of information at
    each call, including the ID numbers, the number of events in each
    histogram, the PROB value, and the maximum Kolmogorov distance between
    the two histograms. For 2-Dim histograms, there are two Kolmogorov
    distances (see below). If ‘N’ is specified, there is a third line of
    output giving the PROB for shape alone, and for normalisation.
    O Overflow, requests that overflow bins be taken into account.
    U Underflow, requests that underflow bins be taken into account.
    L Left: include x-underflows
    R Right: include x-overflows
    T Top: include y-overflows
    B Bottom: include y-underflows
    F1 Histogram 1 has no error (is a function)
    F2 Histogram 2 has no error (is a function)

    Test of compatibility for two 1-Dim histograms ID1 and ID2. A probability
    PROB is calculated as a number between zero and one, where PROB near one
    indicates very similar histograms, and PROB near zero means that it is very
    unlikely that the two arose from the same parent distribution. For two
    histograms sampled randomly from the same distribution, PROB will be
    (approximately) uniformly distributed between 0 and 1. See discussion in
    HBOOK manual under ‘HDIFF- Statistical Considerations’. By default (if no
    options are selected with CHOPT) the comparison is done only on the shape
    of the two histograms, without consideration of the difference in numbers
    of events, and ignoring all underflow and overflow bins.

if you have TH1 *h1 and *h2