Source code for ufl.mathfunctions

"""This module provides basic mathematical functions."""
# Copyright (C) 2008-2016 Martin Sandve Aln├Žs
#
# This file is part of UFL (https://www.fenicsproject.org)
#
# SPDX-License-Identifier:    LGPL-3.0-or-later
#
# Modified by Anders Logg, 2008
# Modified by Kristian B. Oelgaard, 2011

import cmath
import math
import numbers
import warnings

from ufl.constantvalue import (
    ComplexValue,
    ConstantValue,
    FloatValue,
    IntValue,
    RealValue,
    Zero,
    as_ufl,
    is_true_ufl_scalar,
)
from ufl.core.operator import Operator
from ufl.core.ufl_type import ufl_type

"""
TODO: Include additional functions available in <cmath> (need derivatives as well):

Exponential and logarithmic functions:
log10    Compute common logarithm (function)

TODO: Any other useful special functions?

About bessel functions:
http://en.wikipedia.org/wiki/Bessel_function

Portable implementations of bessel functions:
http://www.boost.org/doc/libs/1_47_0/libs/math/doc/sf_and_dist/html/math_toolkit/main_overview/tr1.html

Implementation in C++ std::tr1:: or boost::math::tr1::
- BesselK: cyl_bessel_k(nu, x)
- BesselI: cyl_bessel_i(nu, x)
- BesselJ: cyl_bessel_j(nu, x)
- BesselY: cyl_neumann(nu, x)
"""


# --- Function representations ---


[docs]@ufl_type(is_abstract=True, is_scalar=True, num_ops=1) class MathFunction(Operator): """Base class for all unary scalar math functions.""" # Freeze member variables for objects in this class __slots__ = ("_name",) def __init__(self, name, argument): """Initialise.""" Operator.__init__(self, (argument,)) if not is_true_ufl_scalar(argument): raise ValueError("Expecting scalar argument.") self._name = name
[docs] def evaluate(self, x, mapping, component, index_values): """Evaluate.""" a = self.ufl_operands[0].evaluate(x, mapping, component, index_values) try: if isinstance(a, numbers.Real): res = getattr(math, self._name)(a) else: res = getattr(cmath, self._name)(a) except ValueError: warnings.warn( "Value error in evaluation of function %s with argument %s." % (self._name, a) ) raise return res
def __str__(self): """Format as a string.""" return "%s(%s)" % (self._name, self.ufl_operands[0])
[docs]@ufl_type() class Sqrt(MathFunction): """Square root.""" __slots__ = () def __new__(cls, argument): """Create a new Sqrt.""" if isinstance(argument, (RealValue, Zero, numbers.Real)): if float(argument) < 0: return ComplexValue(cmath.sqrt(complex(argument))) else: return FloatValue(math.sqrt(float(argument))) if isinstance(argument, (ComplexValue, complex)): return ComplexValue(cmath.sqrt(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "sqrt", argument)
[docs]@ufl_type() class Exp(MathFunction): """Exponentiation..""" __slots__ = () def __new__(cls, argument): """Create a new Exp.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.exp(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.exp(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "exp", argument)
[docs]@ufl_type() class Ln(MathFunction): """Natural logarithm.""" __slots__ = () def __new__(cls, argument): """Create a new Ln.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.log(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.log(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "ln", argument)
[docs] def evaluate(self, x, mapping, component, index_values): """Evaluate.""" a = self.ufl_operands[0].evaluate(x, mapping, component, index_values) try: return math.log(a) except TypeError: return cmath.log(a)
[docs]@ufl_type() class Cos(MathFunction): """Cosine.""" __slots__ = () def __new__(cls, argument): """Create a new Cos.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.cos(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.cos(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "cos", argument)
[docs]@ufl_type() class Sin(MathFunction): """Sine.""" __slots__ = () def __new__(cls, argument): """Create a new Sin.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.sin(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.sin(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "sin", argument)
[docs]@ufl_type() class Tan(MathFunction): """Tangent.""" __slots__ = () def __new__(cls, argument): """Create a new Tan.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.tan(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.tan(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "tan", argument)
[docs]@ufl_type() class Cosh(MathFunction): """Hyperbolic cosine.""" __slots__ = () def __new__(cls, argument): """Create a new Cosh.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.cosh(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.cosh(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "cosh", argument)
[docs]@ufl_type() class Sinh(MathFunction): """Hyperbolic sine.""" __slots__ = () def __new__(cls, argument): """Create a new Sinh.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.sinh(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.sinh(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "sinh", argument)
[docs]@ufl_type() class Tanh(MathFunction): """Hyperbolic tangent.""" __slots__ = () def __new__(cls, argument): """Create a new Tanh.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.tanh(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.tanh(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "tanh", argument)
[docs]@ufl_type() class Acos(MathFunction): """Inverse cosine.""" __slots__ = () def __new__(cls, argument): """Create a new Acos.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.acos(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.acos(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "acos", argument)
[docs]@ufl_type() class Asin(MathFunction): """Inverse sine.""" __slots__ = () def __new__(cls, argument): """Create a new Asin.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.asin(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.asin(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "asin", argument)
[docs]@ufl_type() class Atan(MathFunction): """Inverse tangent.""" __slots__ = () def __new__(cls, argument): """Create a new Atan.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.atan(float(argument))) if isinstance(argument, (ComplexValue)): return ComplexValue(cmath.atan(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "atan", argument)
[docs]@ufl_type(is_scalar=True, num_ops=2) class Atan2(Operator): """Inverse tangent with two inputs.""" __slots__ = () def __new__(cls, arg1, arg2): """Create a new Atan2.""" if isinstance(arg1, (RealValue, Zero)) and isinstance(arg2, (RealValue, Zero)): return FloatValue(math.atan2(float(arg1), float(arg2))) if isinstance(arg1, (ComplexValue)) or isinstance(arg2, (ComplexValue)): raise TypeError("Atan2 does not support complex numbers.") return Operator.__new__(cls) def __init__(self, arg1, arg2): """Initialise.""" Operator.__init__(self, (arg1, arg2)) if isinstance(arg1, (ComplexValue, complex)) or isinstance(arg2, (ComplexValue, complex)): raise TypeError("Atan2 does not support complex numbers.") if not is_true_ufl_scalar(arg1): raise ValueError("Expecting scalar argument 1.") if not is_true_ufl_scalar(arg2): raise ValueError("Expecting scalar argument 2.")
[docs] def evaluate(self, x, mapping, component, index_values): """Evaluate.""" a = self.ufl_operands[0].evaluate(x, mapping, component, index_values) b = self.ufl_operands[1].evaluate(x, mapping, component, index_values) try: res = math.atan2(a, b) except TypeError: raise ValueError("Atan2 does not support complex numbers.") except ValueError: warnings.warn( "Value error in evaluation of function atan2 with arguments %s, %s." % (a, b) ) raise return res
def __str__(self): """Format as a string.""" return "atan2(%s,%s)" % (self.ufl_operands[0], self.ufl_operands[1])
[docs]@ufl_type() class Erf(MathFunction): """Erf function.""" __slots__ = () def __new__(cls, argument): """Create a new Erf.""" if isinstance(argument, (RealValue, Zero)): return FloatValue(math.erf(float(argument))) if isinstance(argument, (ConstantValue)): return ComplexValue(math.erf(complex(argument))) return MathFunction.__new__(cls) def __init__(self, argument): """Initialise.""" MathFunction.__init__(self, "erf", argument)
[docs] def evaluate(self, x, mapping, component, index_values): """Evaluate.""" a = self.ufl_operands[0].evaluate(x, mapping, component, index_values) return math.erf(a)
[docs]@ufl_type(is_abstract=True, is_scalar=True, num_ops=2) class BesselFunction(Operator): """Base class for all bessel functions.""" __slots__ = "_name" def __init__(self, name, nu, argument): """Initialise.""" if not is_true_ufl_scalar(nu): raise ValueError("Expecting scalar nu.") if not is_true_ufl_scalar(argument): raise ValueError("Expecting scalar argument.") # Use integer representation if suitable fnu = float(nu) inu = int(nu) if fnu == inu: nu = as_ufl(inu) else: nu = as_ufl(fnu) Operator.__init__(self, (nu, argument)) self._name = name
[docs] def evaluate(self, x, mapping, component, index_values): """Evaluate.""" a = self.ufl_operands[1].evaluate(x, mapping, component, index_values) try: import scipy.special except ImportError: raise ValueError( "You must have scipy installed to evaluate bessel functions in python." ) name = self._name[-1] if isinstance(self.ufl_operands[0], IntValue): nu = int(self.ufl_operands[0]) functype = "n" if name != "i" else "v" else: nu = self.ufl_operands[0].evaluate(x, mapping, component, index_values) functype = "v" func = getattr(scipy.special, name + functype) return func(nu, a)
def __str__(self): """Format as a string.""" return "%s(%s, %s)" % (self._name, self.ufl_operands[0], self.ufl_operands[1])
[docs]@ufl_type() class BesselJ(BesselFunction): """Bessel J function.""" __slots__ = () def __init__(self, nu, argument): """Initialise.""" BesselFunction.__init__(self, "cyl_bessel_j", nu, argument)
[docs]@ufl_type() class BesselY(BesselFunction): """Bessel Y function.""" __slots__ = () def __init__(self, nu, argument): """Initialise.""" BesselFunction.__init__(self, "cyl_bessel_y", nu, argument)
[docs]@ufl_type() class BesselI(BesselFunction): """Bessel I function.""" __slots__ = () def __init__(self, nu, argument): """Initialise.""" BesselFunction.__init__(self, "cyl_bessel_i", nu, argument)
[docs]@ufl_type() class BesselK(BesselFunction): """Bessel K function.""" __slots__ = () def __init__(self, nu, argument): """Initialise.""" BesselFunction.__init__(self, "cyl_bessel_k", nu, argument)