tensor_functions.py 文件源码

def eval_levicivita(*args):
    """Evaluate Levi-Civita symbol."""
    from sympy import factorial
    n = len(args)
    return prod(
        prod(args[j] - args[i] for j in xrange(i + 1, n))
        / factorial(i) for i in xrange(n))
    # converting factorial(i) to int is slightly faster