@tensorflow/tfjs-core/dist/ops/linalg_ops.d.ts

Hardware-accelerated JavaScript library for machine intelligence

/**
 * @license
 * Copyright 2018 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 { Tensor, Tensor1D, Tensor2D } from '../tensor';
import { TensorLike } from '../types';
/**
 * Copy a tensor setting everything outside a central band in each innermost
 * matrix to zero.
 *
 * The band part is computed as follows: Assume input has `k` dimensions
 * `[I, J, K, ..., M, N]`, then the output is a tensor with the same shape where
 * `band[i, j, k, ..., m, n] = in_band(m, n) * input[i, j, k, ..., m, n]`.
 * The indicator function
 * `in_band(m, n) = (num_lower < 0 || (m-n) <= num_lower))`
 * `&& (num_upper < 0 || (n-m) <= num_upper)`
 *
 * ```js
 * const x = tf.tensor2d([[ 0,  1,  2, 3],
 *                        [-1,  0,  1, 2],
 *                        [-2, -1,  0, 1],
 *                        [-3, -2, -1, 0]]);
 * let y = tf.linalg.bandPart(x, 1, -1);
 * y.print(); // [[ 0,  1,  2, 3],
 *            //  [-1,  0,  1, 2],
 *            //  [ 0, -1,  0, 1],
 *            //  [ 0, 0 , -1, 0]]
 * let z = tf.linalg.bandPart(x, 2, 1);
 * z.print(); // [[ 0,  1,  0, 0],
 *            //  [-1,  0,  1, 0],
 *            //  [-2, -1,  0, 1],
 *            //  [ 0, -2, -1, 0]]
 * ```
 *
 * @param x Rank `k` tensor
 * @param numLower Number of subdiagonals to keep.
 *   If negative, keep entire lower triangle.
 * @param numUpper Number of subdiagonals to keep.
 *   If negative, keep entire upper triangle.
 * @returns Rank `k` tensor of the same shape as input.
 *   The extracted banded tensor.
 */
/**
 * @doc {heading:'Operations',
 *       subheading:'Linear Algebra',
 *       namespace:'linalg'}
 */
declare function bandPart_<T extends Tensor>(a: T | TensorLike, numLower: number, numUpper: number): T;
/**
 * Gram-Schmidt orthogonalization.
 *
 * ```js
 * const x = tf.tensor2d([[1, 2], [3, 4]]);
 * let y = tf.linalg.gramSchmidt(x);
 * y.print();
 * console.log('Othogonalized:');
 * y.dot(y.transpose()).print();  // should be nearly the identity matrix.
 * console.log('First row direction maintained:');
 * const data = await y.array();
 * console.log(data[0][1] / data[0][0]);  // should be nearly 2.
 * ```
 *
 * @param xs The vectors to be orthogonalized, in one of the two following
 *   formats:
 *   - An Array of `tf.Tensor1D`.
 *   - A `tf.Tensor2D`, i.e., a matrix, in which case the vectors are the rows
 *     of `xs`.
 *   In each case, all the vectors must have the same length and the length
 *   must be greater than or equal to the number of vectors.
 * @returns The orthogonalized and normalized vectors or matrix.
 *   Orthogonalization means that the vectors or the rows of the matrix
 *   are orthogonal (zero inner products). Normalization means that each
 *   vector or each row of the matrix has an L2 norm that equals `1`.
 */
/**
 * @doc {heading:'Operations',
 *       subheading:'Linear Algebra',
 *       namespace:'linalg'}
 */
declare function gramSchmidt_(xs: Tensor1D[] | Tensor2D): Tensor1D[] | Tensor2D;
/**
 * Compute QR decomposition of m-by-n matrix using Householder transformation.
 *
 * Implementation based on
 *   [http://www.cs.cornell.edu/~bindel/class/cs6210-f09/lec18.pdf]
 * (http://www.cs.cornell.edu/~bindel/class/cs6210-f09/lec18.pdf)
 *
 * ```js
 * const a = tf.tensor2d([[1, 2], [3, 4]]);
 * let [q, r] = tf.linalg.qr(a);
 * console.log('Q');
 * q.print();
 * console.log('R');
 * r.print();
 * console.log('Orthogonalized');
 * q.dot(q.transpose()).print()  // should be nearly the identity matrix.
 * console.log('Reconstructed');
 * q.dot(r).print(); // should be nearly [[1, 2], [3, 4]];
 * ```
 *
 * @param x The `tf.Tensor` to be QR-decomposed. Must have rank >= 2. Suppose
 *   it has the shape `[..., M, N]`.
 * @param fullMatrices An optional boolean parameter. Defaults to `false`.
 *   If `true`, compute full-sized `Q`. If `false` (the default),
 *   compute only the leading N columns of `Q` and `R`.
 * @returns An `Array` of two `tf.Tensor`s: `[Q, R]`. `Q` is a unitary matrix,
 *   i.e., its columns all have unit norm and are mutually orthogonal.
 *   If `M >= N`,
 *     If `fullMatrices` is `false` (default),
 *       - `Q` has a shape of `[..., M, N]`,
 *       - `R` has a shape of `[..., N, N]`.
 *     If `fullMatrices` is `true` (default),
 *       - `Q` has a shape of `[..., M, M]`,
 *       - `R` has a shape of `[..., M, N]`.
 *   If `M < N`,
 *     - `Q` has a shape of `[..., M, M]`,
 *     - `R` has a shape of `[..., M, N]`.
 * @throws If the rank of `x` is less than 2.
 */
/**
 * @doc {heading:'Operations',
 *       subheading:'Linear Algebra',
 *       namespace:'linalg'}
 */
declare function qr_(x: Tensor, fullMatrices?: boolean): [Tensor, Tensor];
export declare const bandPart: typeof bandPart_;
export declare const gramSchmidt: typeof gramSchmidt_;
export declare const qr: typeof qr_;
export {};