> ## Documentation Index
> Fetch the complete documentation index at: https://qi.alphakdb.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Backtesting

## Technical analysis library

Backtesting in qi uses the `qi-ta` library, which is a thin q wrapper around the widely used [ta-lib](https://ta-lib.org). Functions like `bbands` and `atr` are drawn from here.

## QSharpe

For backtesting, **qi** has its own Domain Specific Language (DSL) called **qsharpe**. Below is a sample qsharpe (`.qs`) file:

```
/ strategies/mr1/logic.qs

params:
  bb_n, bb_sd, atr_n, atr_mult

indicators:
  bb  = bbands(close, bb_n, bb_sd, bb_sd, 0)
  vol = atr(atr_n)
  is_oversold = close < bb.lower
  vol_filter  = vol > sma(vol, 50) 

enter:
  is_oversold
  vol_filter

exits:
  stop_loss:
    price: entry_price - (vol * atr_mult)
  
  take_profit:
    price: bb.mid

  stale_exit:
    bars_since_entry > 30
    upnl_r <= 0.5

```

## Parameters

Paramaters are stored in `.params` files, and have the same structure as `.conf` files, e.g.

```
asset=SPY
interval=15
warmup=200
bb_n=20
bb_sd=2.0
atr_n=14
atr_mult=3.0
```

## Folder structure

In any given qi project, qi expects strategies to be stored in a `strategies` folder, under which are folders named after each strategy:

```
strategies/mr1/
 			  |- logic.qs
 			  |- v1.params
 			  |- v2.params
```

## Running a strategy

To run a strategy do:

`q qi.q -strat mr1 -params v1`

The `-params` argument is not required if there is only one `.params` file.

## Shared logic

The folder `strategies/common` is reserved for functionality that can be used by all strategies.

Under common, there can be two folders:

* `lib`	- for `.qs` files with common logic
* `params` - common parameters

## Example using shared logic

If we imagine that we have created the following shared folder:

```
strategies/common/params/
 			  			|- defaults.params
 			  			|- passive.params
 			  			|- aggressive.params
```

We can then create the following:

```
strategies/mr2/
 			  |- logic.qs
```

and run

`q qi.q -strat mr2`

which will use `defaults.params` from `common`, or we can do:

`q qi.q -strat mr2 -params passive`

**Note:** in this second case, `defaults` will still be used, but will be overriden by passive.

If we now create a local params file so that we have:

```
strategies/mr2/
 			  |- logic.qs
 			  |- custom.qs
```

and we now do

`q qi.q -strat mr2`

The order of params files being loaded is:

1. `common/params/defaults.params`
2. `mr2/custom.qs`