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import functools
import numpy as np
from ...tests.helper import pytest
from .. import Time, TimeDelta
allclose_jd = functools.partial(np.allclose, rtol=2. ** -52, atol=0)
allclose_jd2 = functools.partial(np.allclose, rtol=2. ** -52,
atol=2. ** -52) # 20 ps atol
allclose_sec = functools.partial(np.allclose, rtol=2. ** -52,
atol=2. ** -52 * 24 * 3600) # 20 ps atol
dt_tiny = TimeDelta(2. ** -52, format='jd')
def test_addition():
"""Check that an addition at the limit of precision (2^-52) is seen"""
t = Time(2455555., 0.5, format='jd', scale='utc')
t_dt = t + dt_tiny
assert t_dt.jd1 == t.jd1 and t_dt.jd2 != t.jd2
# Check that the addition is exactly reversed by the corresponding subtraction
t2 = t_dt - dt_tiny
assert t2.jd1 == t.jd1 and t2.jd2 == t.jd2
def test_mult_div():
"""Test precision with multiply and divide"""
dt_small = 6 * dt_tiny
# pick a number that will leave remainder if divided by 6.
dt_big = TimeDelta(20000., format='jd')
dt_big_small_by_6 = (dt_big + dt_small) / 6.
dt_frac = dt_big_small_by_6 - TimeDelta(3333., format='jd')
assert allclose_jd2(dt_frac.jd2, 0.33333333333333354)
def test_init_variations():
"""Check that 3 ways of specifying a time + small offset are equivalent"""
dt_tiny_sec = dt_tiny.jd2 * 86400.
t1 = Time(1e11, format='cxcsec') + dt_tiny
t2 = Time(1e11, dt_tiny_sec, format='cxcsec')
t3 = Time(dt_tiny_sec, 1e11, format='cxcsec')
assert t1.jd1 == t2.jd1
assert t1.jd2 == t3.jd2
assert t1.jd1 == t2.jd1
assert t1.jd2 == t3.jd2
def test_precision_exceeds_64bit():
"""
Check that Time object really holds more precision than float64 by looking at the
(naively) summed 64-bit result and asserting equality at the bit level.
"""
t1 = Time(1.23456789e11, format='cxcsec')
t2 = t1 + dt_tiny
assert t1.jd == t2.jd
def test_through_scale_change():
"""Check that precision holds through scale change (cxcsec is TT)"""
t0 = Time(1.0, format='cxcsec')
t1 = Time(1.23456789e11, format='cxcsec')
dt_tt = t1 - t0
dt_tai = t1.tai - t0.tai
assert allclose_jd(dt_tt.jd1, dt_tai.jd1)
assert allclose_jd2(dt_tt.jd2, dt_tai.jd2)
def test_iso_init():
"""Check when initializing from ISO date"""
t1 = Time('2000:001:00:00:00.00000001', scale='tai')
t2 = Time('3000:001:13:00:00.00000002', scale='tai')
dt = t2 - t1
assert allclose_jd2(dt.jd2, 13. / 24. + 1e-8 / 86400. - 1.0)
def test_jd1_is_mult_of_half_or_one():
"""
Check that jd1 is a multiple of 0.5 (note the difference from when Time is created
with a format like 'jd' or 'cxcsec', where jd1 is a multiple of 1.0).
"""
t1 = Time('2000:001:00:00:00.00000001', scale='tai')
assert np.round(t1.jd1 * 2) == t1.jd1 * 2
t1 = Time(1.23456789, 12345678.90123456, format='jd', scale='tai')
assert np.round(t1.jd1) == t1.jd1
@pytest.mark.xfail
def test_precision_neg():
"""
Check precision when jd1 is negative. Currently fails because ERFA routines use a
test like jd1 > jd2 to decide which component to update. Should be
abs(jd1) > abs(jd2).
"""
t1 = Time(-100000.123456, format='jd', scale='tt')
assert np.round(t1.jd1) == t1.jd1
t1_tai = t1.tai
assert np.round(t1_tai.jd1) == t1_tai.jd1
def test_precision_epoch():
"""
Check that input via epoch also has full precision, i.e., against
regression on https://github.com/astropy/astropy/pull/366
"""
t_utc = Time(range(1980, 2001), format='jyear', scale='utc')
t_tai = Time(range(1980, 2001), format='jyear', scale='tai')
dt = t_utc - t_tai
assert allclose_sec(dt.sec, np.round(dt.sec))
def test_leap_seconds_rounded_correctly():
"""Regression tests against #2083, where a leap second was rounded
incorrectly by the underlying ERFA routine."""
t = Time(['2012-06-30 23:59:59.413',
'2012-07-01 00:00:00.413'], scale='ut1', precision=3).utc
assert np.all(t.iso == np.array(['2012-06-30 23:59:60.000',
'2012-07-01 00:00:00.000']))
# with the bug, both yielded '2012-06-30 23:59:60.000'
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