import numpy as np


# 函数
def dis_mats(m, d):  # 以线阵为例
    dis = np.zeros((m, m))
    for i in range(m):
        D = np.arange(0, m * d, d) - d * int(i) * np.ones(m)
        dis[i] = D
    dis = np.triu(dis)
    dis += dis.T - np.diag(dis.diagonal())

    return dis   # 所有阵元的间距的集合


def pn_funcs(f, c, dis):  # 所有阵元的噪声相关性
    k = 2 * np.pi * f / c
    # pn = np.sinc(k * dis)
    a = np.sin(k * dis)
    b = k * dis

    pn = np.divide(a, b, np.ones_like(a), where=b != 0)  # sin0/0=1

    return pn


def ag_funcs(m, pn):
    ps = np.power(m, 2)
    ag_s = ps / np.sum(pn)  #
    ag = 10 * np.log10(ag_s)

    return ag