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from sympy.core.basic import Basic
from sympy.matrices.expressions.matexpr import MatrixExpr
class Transpose(MatrixExpr):
"""
The transpose of a matrix expression.
This is a symbolic object that simply stores its argument without
evaluating it. To actually compute the transpose, use the ``transpose()``
function, or the ``.T`` attribute of matrices.
Examples
========
>>> from sympy import MatrixSymbol, Transpose, transpose
>>> A = MatrixSymbol('A', 3, 5)
>>> B = MatrixSymbol('B', 5, 3)
>>> Transpose(A)
A.T
>>> A.T == transpose(A) == Transpose(A)
True
>>> Transpose(A*B)
(A*B).T
>>> transpose(A*B)
B.T*A.T
"""
is_Transpose = True
def doit(self, **hints):
arg = self.arg
if hints.get('deep', True) and isinstance(arg, Basic):
arg = arg.doit(**hints)
_eval_transpose = getattr(arg, '_eval_transpose', None)
if _eval_transpose is not None:
result = _eval_transpose()
return result if result is not None else Transpose(arg)
else:
return Transpose(arg)
@property
def arg(self):
return self.args[0]
@property
def shape(self):
return self.arg.shape[::-1]
def _entry(self, i, j, expand=False, **kwargs):
return self.arg._entry(j, i, expand=expand, **kwargs)
def _eval_adjoint(self):
return self.arg.conjugate()
def _eval_conjugate(self):
return self.arg.adjoint()
def _eval_transpose(self):
return self.arg
def _eval_trace(self):
from .trace import Trace
return Trace(self.arg) # Trace(X.T) => Trace(X)
def _eval_determinant(self):
from sympy.matrices.expressions.determinant import det
return det(self.arg)
def _eval_derivative(self, x):
# x is a scalar:
return self.arg._eval_derivative(x)
def _eval_derivative_matrix_lines(self, x):
lines = self.args[0]._eval_derivative_matrix_lines(x)
return [i.transpose() for i in lines]
def transpose(expr):
"""Matrix transpose"""
return Transpose(expr).doit(deep=False)
from sympy.assumptions.ask import ask, Q
from sympy.assumptions.refine import handlers_dict
def refine_Transpose(expr, assumptions):
"""
>>> from sympy import MatrixSymbol, Q, assuming, refine
>>> X = MatrixSymbol('X', 2, 2)
>>> X.T
X.T
>>> with assuming(Q.symmetric(X)):
... print(refine(X.T))
X
"""
if ask(Q.symmetric(expr), assumptions):
return expr.arg
return expr
handlers_dict['Transpose'] = refine_Transpose
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