(l-onnx-doc-BlackmanWindow)=

# BlackmanWindow


(l-onnx-op-blackmanwindow-17)=

## BlackmanWindow - 17

### Version

- **name**: [BlackmanWindow (GitHub)](https://github.com/onnx/onnx/blob/main/docs/Operators.md#BlackmanWindow)
- **domain**: `main`
- **since_version**: `17`
- **function**: `True`
- **support_level**: `SupportType.COMMON`
- **shape inference**: `True`

This version of the operator has been available
**since version 17**.

### Summary

Generates a Blackman window as described in the paper https://ieeexplore.ieee.org/document/1455106.

#### Function Body

The function definition for this operator.

```
<
  domain: "",
  opset_import: ["" : 17]
>
BlackmanWindow <periodic,output_datatype>(size) => (output)
{
   A0 = Constant <value: tensor = float {0.42}> ()
   A1 = Constant <value: tensor = float {0.5}> ()
   A2 = Constant <value: tensor = float {0.08}> ()
   Zero = Constant <value: tensor = float {0}> ()
   One = Constant <value: tensor = float {1}> ()
   Two = Constant <value: tensor = float {2}> ()
   Tau = Constant <value: tensor = float {6.28319}> ()
   Periodic_Size_FP = Cast <to: int = 1> (size)
   Symmetric_Size_FP = Sub (Periodic_Size_FP, One)
   IsPeriodic = Constant <value_int: int = @periodic> ()
   IsPeriodic_FP = Cast <to: int = 1> (IsPeriodic)
   IsSymmetric_FP = Sub (One, IsPeriodic_FP)
   Periodic_Component = Mul (Periodic_Size_FP, IsPeriodic_FP)
   Symmetric_Component = Mul (Symmetric_Size_FP, IsSymmetric_FP)
   Size_FP = Add (Periodic_Component, Symmetric_Component)
   AngularIncrement = Div (Tau, Size_FP)
   Range = Range (Zero, Periodic_Size_FP, One)
   RangeAngular = Mul (Range, AngularIncrement)
   TwoRangeAngular = Mul (RangeAngular, Two)
   CosTwoRangeAngular = Cos (TwoRangeAngular)
   A2_Component = Mul (A2, CosTwoRangeAngular)
   CosRangeAngular = Cos (RangeAngular)
   A1_Component = Mul (A1, CosRangeAngular)
   Temp0 = Sub (A0, A1_Component)
   Temp1 = Add (Temp0, A2_Component)
   output = Cast <to: int = @output_datatype> (Temp1)
}
```

### Attributes

* **output_datatype - INT** (default is `'1'`):

  The data type of the output tensor. Strictly must be one of the values from DataType enum in TensorProto whose values correspond to T2. The default value is 1 = FLOAT.

* **periodic - INT** (default is `'1'`):

  If 1, returns a window to be used as periodic function. If 0, return a symmetric window. When 'periodic' is specified, hann computes a window of length size + 1 and returns the first size points. The default value is 1.

### Inputs

- **size** (heterogeneous) - **T1**:

  A scalar value indicating the length of the window.

### Outputs

- **output** (heterogeneous) - **T2**:

  A Blackman window with length: size. The output has the shape: [size].

### Type Constraints

* **T1** in ( `tensor(int32)`, `tensor(int64)` ):

  Constrain the input size to int32_t or int64_t.
* **T2** in ( `tensor(bfloat16)`, `tensor(double)`, `tensor(float)`, `tensor(float16)`, `tensor(int16)`, `tensor(int32)`, `tensor(int64)`, `tensor(int8)`, `tensor(uint16)`, `tensor(uint32)`, `tensor(uint64)`, `tensor(uint8)` ):

  Constrain output types to numeric tensors.