Why is the square root not included in the log RMS formula used to calculate SpO2 in MAX30100_SpO2Calculator.cpp?

[jeeeej]

Hello!
I have been trying to understand the equation used to calculate SpO2 in the library:
`void SpO2Calculator::update(float irACValue, float redACValue, bool beatDetected)
{
irACValueSqSum += irACValue * irACValue;
redACValueSqSum += redACValue * redACValue;
++samplesRecorded;

if (beatDetected) {
    ++beatsDetectedNum;
    if (beatsDetectedNum == CALCULATE_EVERY_N_BEATS) {
        float acSqRatio = 100.0 * log(redACValueSqSum/samplesRecorded) / log(irACValueSqSum/samplesRecorded);
        uint8_t index = 0;

        if (acSqRatio > 66) {
            index = (uint8_t)acSqRatio - 66;
        } else if (acSqRatio > 50) {
            index = (uint8_t)acSqRatio - 50;
        }
        reset();

        spO2 = spO2LUT[index];
    }
}

}`

I am currently stuck trying to understand why a root for each of the mean squares of IR and R was not included in the log equation used to determine ac square ratio, despite presumably referencing the log of root mean square method from A Single-Chip Pulsoximeter Design Using the MSP430 application report.

An explanation would be appreciated.