The Relative Strength Index, popularly known as RSI, is a technical analysis indicator used to measure the momentum of an asset and identify overbought or oversold conditions. The RSI is typically calculated using a formula that compares the average gains and losses over a specified period of time, which is usually 14 days.

The RSI ranges from 0 to 100, with readings above 70 typically indicating an overbought condition and readings below 30 indicating an oversold condition. Traders often use the RSI to identify potential trend reversals, as well as to confirm the strength of existing trends.

To calculate the Relative Strength Index (RSI), you can use the following formula:

RSI = 100 - (100 / (1 + RS))

where RS is the average of the gains over a specified period of time divided by the average of the losses over the same period of time.

**Example:**

Let's say you want to calculate the RSI for a stock over a period of 14 days. You would start by calculating the average gain and average loss over the 14-day period. Let's assume that the stock had the following closing prices over the 14-day period:

Day 1: $10, Day 2: $12, Day 3: $11, Day 4: $9, Day 5: $8, Day 6: $10, Day 7: $11, Day 8: $12, Day 9: $13, Day 10: $14, Day 11: $12, Day 12: $10, Day 13: $9, Day 14: $11.

To calculate the average gain and average loss, you would first calculate the daily changes in price as follows:

Day 2: +$2, Day 3: -$1, Day 4: -$2, Day 5: -$1, Day 6: +$2, Day 7: +$1, Day 8: +$1, Day 9: +$1, Day 10: +$1, Day 11: -$2, Day 12: -$2, Day 13: -$1, Day 14: +$2.

Next, you would calculate the average gain and average loss over the 14-day period. Let's assume that the average gain is $1.29 and the average loss is $1.14.

Using the RSI formula, we can calculate the RSI as follows:

RSI = 100 - (100 / (1 + (1.29 / 1.14))) = 100 - (100 / (1 + 1.13)) = 53.42

So the RSI for the stock over the 14-day period is 53.42. This suggests that the stock is not currently overbought or oversold and is trading in a range.