Source code for mars.tensor.arithmetic.arctan2

#!/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
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# distributed under the License is distributed on an "AS IS" BASIS,
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# limitations under the License.

import numpy as np

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

class TensorArctan2(TensorBinOp):
    _op_type_ = OperandDef.ARCTAN2
    _func_name = "arctan2"

    def _is_sparse(cls, x1, x2):
        if hasattr(x1, "issparse") and x1.issparse():
            # if x1 is sparse, will be sparse always
            return True
        elif np.isscalar(x1) and x1 == 0:
            # x1 == 0, return sparse if x2 is
            return x2.issparse() if hasattr(x2, "issparse") else False
        return False

[docs]@infer_dtype(np.arctan2) def arctan2(x1, x2, out=None, where=None, **kwargs): """ Element-wise arc tangent of ``x1/x2`` choosing the quadrant correctly. The quadrant (i.e., branch) is chosen so that ``arctan2(x1, x2)`` is the signed angle in radians between the ray ending at the origin and passing through the point (1,0), and the ray ending at the origin and passing through the point (`x2`, `x1`). (Note the role reversal: the "`y`-coordinate" is the first function parameter, the "`x`-coordinate" is the second.) By IEEE convention, this function is defined for `x2` = +/-0 and for either or both of `x1` and `x2` = +/-inf (see Notes for specific values). This function is not defined for complex-valued arguments; for the so-called argument of complex values, use `angle`. Parameters ---------- x1 : array_like, real-valued `y`-coordinates. x2 : array_like, real-valued `x`-coordinates. `x2` must be broadcastable to match the shape of `x1` or vice versa. 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 Returns ------- angle : Tensor Array of angles in radians, in the range ``[-pi, pi]``. See Also -------- arctan, tan, angle Notes ----- *arctan2* is identical to the `atan2` function of the underlying C library. The following special values are defined in the C standard: [1]_ ====== ====== ================ `x1` `x2` `arctan2(x1,x2)` ====== ====== ================ +/- 0 +0 +/- 0 +/- 0 -0 +/- pi > 0 +/-inf +0 / +pi < 0 +/-inf -0 / -pi +/-inf +inf +/- (pi/4) +/-inf -inf +/- (3*pi/4) ====== ====== ================ Note that +0 and -0 are distinct floating point numbers, as are +inf and -inf. References ---------- .. [1] ISO/IEC standard 9899:1999, "Programming language C." Examples -------- Consider four points in different quadrants: >>> import mars.tensor as mt >>> x = mt.array([-1, +1, +1, -1]) >>> y = mt.array([-1, -1, +1, +1]) >>> (mt.arctan2(y, x) * 180 / mt.pi).execute() array([-135., -45., 45., 135.]) Note the order of the parameters. `arctan2` is defined also when `x2` = 0 and at several other special points, obtaining values in the range ``[-pi, pi]``: >>> mt.arctan2([1., -1.], [0., 0.]).execute() array([ 1.57079633, -1.57079633]) >>> mt.arctan2([0., 0., mt.inf], [+0., -0., mt.inf]).execute() array([ 0. , 3.14159265, 0.78539816]) """ op = TensorArctan2(**kwargs) return op(x1, x2, out=out, where=where)