Simply put, Force Index by Alexander Elder is an EMA of a "raw" Force Index, which is:

# raw force index

RFI = Volume * (Close - Prev Close)

To initialize the EMA of RFI, you'd need to do a basic Simple Moving Average (SMA) of the first Period bars of the daily RFI. Without this initialization, you're essentially using 0 as the initialization, which is not terrible, but it might take an extra 100-200 bars before it converges to acceptable accuracy due to the way EMA works.

Other than that, from what I can tell, your formula appears mostly correct. My open-source C# .NET library includes the formula for Force Index and a manually calculated Excel spreadsheet. Might be worth a comparison.

Simply put, Force Index by Alexander Elder is an EMA of a "raw" Force Index, which is:

# raw force index

RFI = Volume * (Close - Prev Close)

To initialize the EMA of RFI, you'd need to do a basic Simple Moving Average (SMA) of the first Period bars of the daily RFI. Without this initialization, you're essentially using 0 as the initialization, which is not terrible, but it might take an extra 100-200 bars before it converges to acceptable accuracy due to the way EMA works.

# EMA of RFI
# For the first instance, substitute SMA of RFI for Previous Force Index (not shown)

k = 2 / (Period + 1)
ForceIndex = Prev Force Index + k * (RFI - Previous Force Index)

From what I can tell, your final formula appears to be correct. My open-source C# .NET library includes the formula for Force Index and a manually calculated Excel spreadsheet. Might be worth a comparison.

Simply put, Force Index by Alexander Elder is an EMA of a "raw" Force Index, which is:

# raw force index

RFI = Volume * (Close - Prev Close)

To initialize the EMA of RFI, you'd need to do a basic Simple Moving Average (SMA) of the first size_t bars of RFI (you call it daily).

Other than that, from what I can tell, your formula appears mostly correct, except for the EMA initialization with SMA. My open-source C# .NET library includes the formula for Force Index and a manually calculated Excel spreadsheet. Might be worth a comparison.

Simply put, Force Index by Alexander Elder is an EMA of a "raw" Force Index, which is:

# raw force index

RFI = Volume * (Close - Prev Close)

To initialize the EMA of RFI, you'd need to do a basic Simple Moving Average (SMA) of the first Period bars of the daily RFI. Without this initialization, you're essentially using 0 as the initialization, which is not terrible, but it might take an extra 100-200 bars before it converges to acceptable accuracy due to the way EMA works.

Other than that, from what I can tell, your formula appears mostly correct. My open-source C# .NET library includes the formula for Force Index and a manually calculated Excel spreadsheet. Might be worth a comparison.