Source code for picos.expressions.cone_expcone

# ------------------------------------------------------------------------------
# Copyright (C) 2019 Maximilian Stahlberg
# Based on the original picos.expressions module by Guillaume Sagnol.
# This file is part of PICOS.
# PICOS is free software: you can redistribute it and/or modify it under the
# terms of the GNU General Public License as published by the Free Software
# Foundation, either version 3 of the License, or (at your option) any later
# version.
# PICOS is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
# You should have received a copy of the GNU General Public License along with
# this program.  If not, see <>.
# ------------------------------------------------------------------------------

"""Implements :class:`ExponentialCone`."""

import operator
from collections import namedtuple

from .. import glyphs
from ..apidoc import api_end, api_start
from ..constraints import ExpConeConstraint
from .cone import Cone
from .exp_affine import AffineExpression

_API_START = api_start(globals())
# -------------------------------

[docs]class ExponentialCone(Cone): r"""The exponential cone. Represents the convex cone :math:`\operatorname{cl}\{(x,y,z): y \exp(\frac{z}{y}) \leq x, x,y > 0\}`. """
[docs] def __init__(self): """Construct an exponential cone.""" typeStr = "Exponential Cone" symbStr = glyphs.closure(glyphs.set(glyphs.sep( glyphs.col_vectorize("x", "y", "z"), ", ".join([ glyphs.le( glyphs.mul("y", glyphs.exp(glyphs.div("z", "y"))), "x"),"x", 0),"y", 0) ])))) Cone.__init__(self, 3, typeStr, symbStr)
def _get_mutables(self): return frozenset() def _replace_mutables(self): return self Subtype = namedtuple("Subtype", ()) def _get_subtype(self): return self.Subtype() @classmethod def _predict(cls, subtype, relation, other): assert isinstance(subtype, cls.Subtype) if relation == operator.__rshift__: if issubclass(other.clstype, AffineExpression): if other.subtype.dim == 3: return ExpConeConstraint.make_type() return Cone._predict_base(cls, subtype, relation, other) def _rshift_implementation(self, element): if isinstance(element, AffineExpression): if len(element) != 3: raise TypeError("Elements of the exponential cone must be " "three-dimensional.") return ExpConeConstraint(element) # Handle scenario uncertainty for all cones. return Cone._rshift_base(self, element) @property def dual_cone(self): """Implement :attr:`.cone.Cone.dual_cone`.""" raise NotImplementedError( "PICOS does not have an explicit representation for the dual of " "the exponential cone yet.")
# -------------------------------------- __all__ = api_end(_API_START, globals())