function Subtract1d( mergedElements ) {

	// Subtract1d inherits from abstract strategy "StableMerge1d".
	
	StableMerge1d.call( this, mergedElements );

	this.strategyType = "Subtract1d";

}
Subtract1d, can be initialized by StrategyFactory directly.
MergeStrategy for MergedLayer when apply Subtract operation to 1d TensorSpace layers.

For example:
```javascript
let dense1 = new TSP.layers.Dense({ ...config });
let dense2 = new TSP.layers.Dense({ ...config });
let subtractLayer = TSP.layers.Subtract([ dense1, dense2 ], { ...config });
```
In this example, the merged layer "subtractLayer" apply merge strategy "Subtract1d".

@param mergedElements, array of TensorSpace layers. (layerList.length > 0)
@constructor