matmul.py 文件源码

def merge_explicit(matmul):
    """ Merge explicit MatrixBase arguments

    >>> from sympy import MatrixSymbol, eye, Matrix, MatMul, pprint
    >>> from sympy.matrices.expressions.matmul import merge_explicit
    >>> A = MatrixSymbol('A', 2, 2)
    >>> B = Matrix([[1, 1], [1, 1]])
    >>> C = Matrix([[1, 2], [3, 4]])
    >>> X = MatMul(A, B, C)
    >>> pprint(X)
      [1  1] [1  2]
    A*[    ]*[    ]
      [1  1] [3  4]
    >>> pprint(merge_explicit(X))
      [4  6]
    A*[    ]
      [4  6]

    >>> X = MatMul(B, A, C)
    >>> pprint(X)
    [1  1]   [1  2]
    [    ]*A*[    ]
    [1  1]   [3  4]
    >>> pprint(merge_explicit(X))
    [1  1]   [1  2]
    [    ]*A*[    ]
    [1  1]   [3  4]
    """
    if not any(isinstance(arg, MatrixBase) for arg in matmul.args):
        return matmul
    newargs = []
    last = matmul.args[0]
    for arg in matmul.args[1:]:
        if isinstance(arg, (MatrixBase, Number)) and isinstance(last, (MatrixBase, Number)):
            last = last * arg
        else:
            newargs.append(last)
            last = arg
    newargs.append(last)

    return MatMul(*newargs)