Source code for mars.tensor.arithmetic.exp

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright 1999-2021 Alibaba Group Holding Ltd.
# 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
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

import numpy as np

from ... import opcodes as OperandDef
from ..utils import infer_dtype
from .core import TensorUnaryOp
from .utils import arithmetic_operand

class TensorExp(TensorUnaryOp):
    _op_type_ = OperandDef.EXP
    _func_name = "exp"

[docs]@infer_dtype(np.exp) def exp(x, out=None, where=None, **kwargs): r""" Calculate the exponential of all elements in the input tensor. Parameters ---------- x : array_like Input values. out : Tensor, None, or tuple of Tensor and None, optional A location into which the result is stored. If provided, it must have a shape that the inputs broadcast to. If not provided or `None`, a freshly-allocated tensor is returned. A tuple (possible only as a keyword argument) must have length equal to the number of outputs. where : array_like, optional Values of True indicate to calculate the ufunc at that position, values of False indicate to leave the value in the output alone. **kwargs For other keyword-only arguments, see the :ref:`ufunc docs <ufuncs.kwargs>`. Returns ------- out : Tensor Output tensor, element-wise exponential of `x`. See Also -------- expm1 : Calculate ``exp(x) - 1`` for all elements in the array. exp2 : Calculate ``2**x`` for all elements in the array. Notes ----- The irrational number ``e`` is also known as Euler's number. It is approximately 2.718281, and is the base of the natural logarithm, ``ln`` (this means that, if :math:`x = \ln y = \log_e y`, then :math:`e^x = y`. For real input, ``exp(x)`` is always positive. For complex arguments, ``x = a + ib``, we can write :math:`e^x = e^a e^{ib}`. The first term, :math:`e^a`, is already known (it is the real argument, described above). The second term, :math:`e^{ib}`, is :math:`\cos b + i \sin b`, a function with magnitude 1 and a periodic phase. References ---------- .. [1] Wikipedia, "Exponential function", .. [2] M. Abramovitz and I. A. Stegun, "Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables," Dover, 1964, p. 69, Examples -------- Plot the magnitude and phase of ``exp(x)`` in the complex plane: >>> import mars.tensor as mt >>> import matplotlib.pyplot as plt >>> x = mt.linspace(-2*mt.pi, 2*mt.pi, 100) >>> xx = x + 1j * x[:, mt.newaxis] # a + ib over complex plane >>> out = mt.exp(xx) >>> plt.subplot(121) >>> plt.imshow(mt.abs(out).execute(), ... extent=[-2*mt.pi, 2*mt.pi, -2*mt.pi, 2*mt.pi], cmap='gray') >>> plt.title('Magnitude of exp(x)') >>> plt.subplot(122) >>> plt.imshow(mt.angle(out).execute(), ... extent=[-2*mt.pi, 2*mt.pi, -2*mt.pi, 2*mt.pi], cmap='hsv') >>> plt.title('Phase (angle) of exp(x)') >>> """ op = TensorExp(**kwargs) return op(x, out=out, where=where)