在Numpy中检查矩阵是否对称 [英] Checking if a matrix is symmetric in Numpy

问题描述

我正在尝试使用参数(a,tol=1e-8)创建一个函数，该函数返回一个布尔值，该布尔值告诉用户矩阵是否对称(对称矩阵等于其转置矩阵).到目前为止，我有:

I'm trying to make a function with the arguments (a,tol=1e-8) that returns a boolean value that tells the user whether or not the matrix is symmetric (symmetric matrix is equal to its transpose). So far I have:

def check_symmetric(a, tol=1e-8):
if np.transpose(a, axes=axes) == np.transpose(a, axes=axes):
    return True
def sqr(s):
    rows = len(s)
    for row in sq:
        if len(row) != rows:
            return False
    return True
if a != sqr(s):
    raise ValueError

尽管我一直收到一条axes isn't defined消息，所以我很确定这根本不起作用……我想通过的测试是:

although I keep getting an axes isn't defined message so I'm pretty sure that doesn't work at all...... the tests I'd like to pass are:

e = np.eye(4)
f = np.diag([1], k=3)
g = e[1:, :]

print(check_symmetric(e))
print(not check_symmetric(e + f))
print(check_symmetric(e + f * 1e-9))
print(not check_symmetric(e + f * 1e-9, 1e-10))
try:
    check_symmetric(g)
    print(False)
except ValueError:
    print(True)

感谢您的帮助，谢谢！

推荐答案

您可以简单地使用allclose

def check_symmetric(a, rtol=1e-05, atol=1e-08):
    return numpy.allclose(a, a.T, rtol=rtol, atol=atol)

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