# Source code for ufl.algorithms.elementtransformations

```# -*- coding: utf-8 -*-
"""This module provides helper functions to
- UFL algorithms taking care of underspecified DOLFIN expressions."""

# Copyright (C) 2012 Marie E. Rognes, 2015 Jan Blechta
#
# This file is part of UFL (https://www.fenicsproject.org)
#

from ufl.log import error
from ufl.finiteelement import FiniteElement, VectorElement, TensorElement, \
MixedElement, EnrichedElement, NodalEnrichedElement

__all__ = ['increase_order', 'tear']

[docs]def increase_order(element):
"Return element of same family, but a polynomial degree higher."
return _increase_degree(element, +1)

def change_regularity(element, family):
"""
For a given finite element, return the corresponding space
specified by 'family'.
"""
return element.reconstruct(family=family)

[docs]def tear(element):
"For a finite element, return the corresponding discontinuous element."
return change_regularity(element, "DG")

def _increase_degree(element, degree_rise):
if isinstance(element, (FiniteElement, VectorElement, TensorElement)):
# Can't increase degree for reals
if element.family() == "Real":
return element
return element.reconstruct(degree=(element.degree() + degree_rise))
elif isinstance(element, MixedElement):
return MixedElement([_increase_degree(e, degree_rise)
for e in element.sub_elements()])
elif isinstance(element, EnrichedElement):
return EnrichedElement([_increase_degree(e, degree_rise)
for e in element.sub_elements()])
elif isinstance(element, NodalEnrichedElement):
return NodalEnrichedElement([_increase_degree(e, degree_rise)
for e in element.sub_elements()])
else:
error("Element reconstruction is only done to stay compatible"
" with hacks in DOLFIN. Not expecting a %s" % repr(element))
```