import numpy as np
import sobol_lib as sbl

seed_init = 15
seed = seed_init

def resetSobolSeed():
    global seed
    global seed_init
    seed = seed_init
    
def setSobolInitSeed(seed_init_new):
    global seed_init
    seed_init = seed_init_new
    
def incSobolSeed(n):
    global seed
    seed += n

def getNextSobol(dim = 1):
    global seed
    x, seed = sbl.i4_sobol(dim, seed)
    return np.array(x)

def uni01_to_normal(x_uni):
    assert len(x_uni) % 2 == 0
    x_normal = np.empty(len(x_uni))
    for i in range(len(x_uni)//2):
        phi = x_uni[2*i]*2*np.pi
        r   = np.sqrt(- 2*np.log(1-x_uni[2*i+1]))
        z = r * np.exp(1j*phi)
        x_normal[2*i]   = np.real(z)
        x_normal[2*i+1] = np.imag(z)
    return x_normal