双布林Dual Bollinger Bands

This technical indicator combines dual Bollinger Bands with multiple moving average overlays to provide a comprehensive view of price trends, volatility, and potential support/resistance zones.

**Components:**

1. **TEMA21 (Triple Exponential Moving Average)**
- Yellow line representing the 21-period TEMA
- Provides smooth trend direction with reduced lag compared to traditional moving averages
- Calculated using three sequential EMAs to filter out market noise

2. **SMA21 & EMA21 Channel**
- Green filled area between the 21-period Simple Moving Average and Exponential Moving Average
- Visualizes the dynamic zone where these two averages interact
- Helps identify trend strength when price stays above/below this channel

3. **MA21 (Simple Moving Average)**
- Bright green line showing the 21-period SMA
- Classic trend-following indicator

4. **EMA21 (Exponential Moving Average)**
- Dark green line displaying the 21-period EMA
- More responsive to recent price changes than SMA

5. **Dual Bollinger Bands**
- **Outer Bands (2 Standard Deviations)**: Orange lines marking the traditional Bollinger Band boundaries
- **Inner Bands (1 Standard Deviation)**: Orange lines creating a tighter volatility zone
- **Orange Shaded Areas**: Highlight the zones between outer and inner bands
- All bands use a 21-period basis and are fully customizable

**Settings:**
- Length: 21 (adjustable)
- Source: Close price (adjustable)
- Outer Band StdDev: 2.0 (adjustable)
- Inner Band StdDev: 1.0 (adjustable)
- Offset: 0 (adjustable from -500 to +500)

**Usage:**
This indicator is ideal for identifying trend direction, volatility expansion/contraction, and potential reversal zones. The dual Bollinger Bands provide multiple levels for support/resistance analysis, while the moving averages confirm trend strength and direction.