/**
 * @license
 * Copyright 2019 Google LLC. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * =============================================================================
 */

import {Tensor1D} from '../../tensor';
import {op} from '../operation';
import {cosineWindow} from '../signal_ops_util';

/**
 * Generate a Hann window.
 *
 * See: https://en.wikipedia.org/wiki/Window_function#Hann_and_Hamming_windows
 *
 * ```js
 * tf.signal.hannWindow(10).print();
 * ```
 * @param The length of window
 *
 * @doc {heading: 'Operations', subheading: 'Signal', namespace: 'signal'}
 */
function hannWindow_(windowLength: number): Tensor1D {
  return cosineWindow(windowLength, 0.5, 0.5);
}

export const hannWindow = op({hannWindow_});