VariablePeriodMFI

Background

The Money Flow Index (MFI) is a momentum oscillator that brings volume into the picture. It works much like the RSI, but instead of looking at price changes alone it weights each bar by the raw money flow (price multiplied by volume). Because of this it is sometimes called a "volume-weighted RSI." Readings run from 0 to 100, and the oscillator is used to gauge buying and selling pressure behind a move.

A standard MFI uses a fixed look-back. VariablePeriodMFI takes a period for each bar, letting the window adapt to market conditions. The per-bar periods normally come from an adaptor such as the DominantCycle. This implementation uses the current chart's volume internally, so only price and the periods array are passed in.

Included formula

The toolbox ships a ready-made Adaptive Smoothed MFI indicator built on this function, so you can use it without writing any code. In AmiBroker open the Charts window, expand the WiseTraderToolbox group and drag Adaptive Smoothed MFI onto a chart.

It plots the Money Flow Index in its own pane below price. The Adaptor you pick is what produces the per-bar period this function needs — so the look-back adapts to the market — and an optional Smoother cleans up the input first. The adaptor's bounds, the smoothing and the colours are all set from the indicator's parameters.

The exported function

If you would rather build your own formula, the toolbox exports the calculation as a single AFL function you can call directly — it is the engine inside that indicator.

Usage

periods = DominantCycle( Close );
mfi = VariablePeriodMFI( ( High + Low + Close ) / 3, periods );
Plot( mfi, "Adaptive MFI", colorRed );
Plot( 80, "", colorGrey40, styleDashed | styleNoLabel );
Plot( 20, "", colorGrey40, styleDashed | styleNoLabel );