"""
A Bose-Einstein condensate
==========================

``GPE`` solves the Gross-Pitaevskii equation in atomic units rather than optical ones.
"""

import numpy as np
from NLSE import GPE
from scipy.constants import atomic_mass

PRECISION_COMPLEX = np.complex64
PRECISION_REAL = np.float32

N = 2048
N_at = 1e6
g = 1e3 / (N_at / 1e-3**2)
waist = 1e-3
window = 1e-3
m = 87 * atomic_mass


def main():
    simu_gpe = GPE(
        gamma=0,
        N=N_at,
        window=window,
        g=g,
        V=None,
        m=m,
        NX=N,
        NY=N,
        backend="CUPY",
    )
    psi_0 = np.exp(-(simu_gpe.XX**2 + simu_gpe.YY**2) / waist**2).astype(
        PRECISION_COMPLEX
    )
    simu_gpe.out_field(psi_0, 1e-6, verbose=True, plot=True, splitting="lie")


if __name__ == "__main__":
    main()