the regular math formula for "Calculating the index value of a sequence based on a given sequence value." in PineScript

Question

I am getting errors on how to do this currentIndex = ceil((sqrt(8 * sequenceValue + 1) - 1) / 2) in Pinescript

Currently at // Update currentIndex based on sequenceValue currentIndex := round((sqrt(float(8 * sequenceValue + 1)) - 1) / 2, round_half_up) any help would be appreciated.

The regular math formula for the expression ceil((sqrt(8 * sequenceValue + 1) - 1) / 2) is as follows:

1. Evaluate the innermost expression: 8 * sequenceValue + 1.
2. Take the square root of the result from step 1: sqrt(8 * sequenceValue + 1).
3. Subtract 1 from the result from step 2: sqrt(8 * sequenceValue + 1) - 1.
4. Divide the result from step 3 by 2: (sqrt(8 * sequenceValue + 1) - 1) / 2.
5. Apply the ceiling function to the result from step 4: ceil((sqrt(8 * sequenceValue + 1) - 1) / 2).

In summary, the formula calculates the square root of (8 * sequenceValue + 1), subtracts 1, divides by 2, and then rounds up to the nearest integer using the ceiling function.