from sympy import symbols, sin, srepr
x, y, z = symbols('x y z')                                                             
z = x * y                                                                                  
sin_z = sin(z)                                                                     
expr = sin_z / 2
print(expr)
print(srepr(expr))

sin(x*y)/2
Mul(Rational(1, 2), sin(Mul(Symbol('x'), Symbol('y'))))

from sympy import preorder_traversal
for arg in preorder_traversal(expr):                                                
    print(arg)

sin(x*y)/2
1/2
sin(x*y)
x*y
x
y

from sympy import postorder_traversal
for arg in postorder_traversal(expr):                                                
    print(arg)

1/2
x
y
x*y
sin(x*y)
sin(x*y)/2

from sympy import MatrixSymbol, Matrix

A = MatrixSymbol('A', 4, 4)
B = MatrixSymbol('B', 4, 4)

print(A)

A

print(srepr(A))

MatrixSymbol('A', Integer(4), Integer(4))

C = A + B
print(C)
print(srepr(C))

A + B
MatAdd(MatrixSymbol('A', Integer(4), Integer(4)), MatrixSymbol('B', Integer(4), Integer(4)))

A1 = A[:2, :]
A2 = A[2:, :]
print(A1)
print(srepr(A1))

A[:2, :4]
MatrixSlice(MatrixSymbol('A', Integer(4), Integer(4)), Tuple(Integer(0), Integer(2), Integer(1)), Tuple(Integer(0), Integer(4), Integer(1)))

A_ = Matrix(A1).row_join(Matrix(A2))
print(A_)

Matrix([[A[0, 0], A[0, 1], A[0, 2], A[0, 3], A[2, 0], A[2, 1], A[2, 2], A[2, 3]], [A[1, 0], A[1, 1], A[1, 2], A[1, 3], A[3, 0], A[3, 1], A[3, 2], A[3, 3]]])