OBV logic in AB

[BBands]

I am wondering about the OBV() logic in AB. Is it this?

if Close > Close[-1]: temp = +volume
if Close < Close[-1]: temp = -volume
if Close == Close: temp = 0
cumsum(temp)

Thanks,

John

[fxshrat]

It is one line

function cOBV() {
    // https://forum.amibroker.com/t/obv-logic-in-ab/23785
    return Cum(sign(ROC(C,1))*V)+V[0]; 
}

Plot( cOBV(), "cOBV", colorOrange, styleLine );
Plot( OBV(), "OBV", colorRed, styleLine );

[BBands]

Thanks. The core logic is as I understand it should be, but why include the volume of the first bar?

[fxshrat]

Because ROC is NULL on first element.

I actually forgot to add Nz().
So here is update

function cOBV() {
    // https://forum.amibroker.com/t/obv-logic-in-ab/23785
    rc = Nz(ROC(C,1));
    return Cum(sign(rc)*V) + V[0]; 
}

Plot( cOBV(), "cOBV", colorOrange, styleLine );
Plot( OBV(), "OBV", colorRed, styleLine );