#!/usr/bin/env python3
#
# Authors: Christoph Lehner 2020
#
# Desc.: Pion and vector propagator from a point source at the origin
#
import gpt as g

# load gauge field and describe fermion
gauge = g.qcd.gaugefield("params.txt")
light = g.qcd.fermion("light.txt")

# create point source
src = g.qcd.propagator(gauge.dp.grid)
g.create.point(src, [0, 0, 0, 0])

# solve
prop = light.solve.exact(src)

# pion
corr_pion = g.slice(g.adj(prop) * prop, 3)
print("Pion two point:")
print(corr_pion)

# vector
gamma = g.qcd.gamma
corr_vector = g.slice(gamma[0] * g.adj(prop) * gamma[0] * prop, 3)
print("Vector two point:")
print(corr_vector)