Two state algorithms, not interchangeable stop settings
This comparison follows TradingView's documented built-in calculations. Community scripts can change the source, smoothing or reversal test. M means (high + low) / 2; m is the Supertrend multiplier; EP is SAR's extreme point; AF is its acceleration factor. A plotted indicator is not itself a broker stop order.
- Increasing the Supertrend multiplier widens its basic bands; its carried band need not move away from price on that bar. An ATR spike therefore does not automatically loosen the active line.
- An outside bar can reverse SAR and extend the old trend extreme at the same time. From SAR 97, EP 100 and AF 0.02, a bar with high 103 and low 96 reverses down to 103 before the two-bar constraint, not to 100. The simple phrase reset to prior EP misses this case.
- SAR continues moving toward EP even without a fresh extreme. AF only increases on a new extreme, not merely because another bar elapsed. The two-bar clamp can also prevent the projected movement.
| State or update | Supertrend | Parabolic SAR |
|---|---|---|
| Candidate value | Basic bands: M + m × ATR and M − m × ATR. | Projected SAR = previous SAR + previous AF × (previous EP − previous SAR). |
| Memory | Upper band resets if the basic upper is lower, or the previous close exceeded the previous upper. Otherwise retain it. Lower band resets if the basic lower is higher, or the previous close was below the previous lower. | EP is the highest high in an up leg or lowest low in a down leg. A new extreme increases AF by its increment, capped at its maximum. |
| Reversal | From down: close above the current upper band switches up. From up: close below the current lower band switches down. Equality holds direction. | From up: low below projected SAR reverses. From down: high above projected SAR reverses. Strict penetration is required. On a reversal down, reset SAR to max(current high, prior EP); on a reversal up, use min(current low, prior EP). Reset AF to its start value and EP to the new leg's extreme before the historical constraint. |
| Output and constraint | Plot lower band while up; upper band while down. | After either branch, cap an uptrend point at the lower of the two preceding lows; floor a downtrend point at the higher of the two preceding highs. Apply the constraint using the resulting direction, including reversal bars. |