!pip install -I "phoebe>=2.2,<2.3"

"""
Explanation: Distance
Setup
Let's first make sure we have the latest version of PHOEBE 2.2 installed. (You can comment out this line if you don't use pip for your installation or don't want to update to the latest release).
End of explanation
"""


%matplotlib inline

import phoebe
from phoebe import u # units
import numpy as np
import matplotlib.pyplot as plt

logger = phoebe.logger()

b = phoebe.default_binary()

"""
Explanation: As always, let's do imports and initialize a logger and a new bundle.  See Building a System for more details.
End of explanation
"""


print(b.get_parameter(qualifier='distance', context='system'))

print(b.get_parameter(qualifier='t0', context='system'))

"""
Explanation: Relevant Parameters
The 'distance' parameter lives in the 'system' context and is simply the distance between the center of the coordinate system and the observer (at t0)
End of explanation
"""


b.add_dataset('orb', times=np.linspace(0,3,101), dataset='orb01')

b.set_value('distance', 1.0)

b.run_compute(model='dist1')

b.set_value('distance', 2.0)

b.run_compute(model='dist2')

afig, mplfig = b['orb01'].plot(y='ws', show=True, legend=True)

"""
Explanation: Influence on Orbits (Positions)
The distance has absolutely NO effect on the synthetic orbit as the origin of the orbit's coordinate system is such that the barycenter of the system is at 0,0,0 at t0.
To demonstrate this, let's create an 'orb' dataset and compute models at both 1 m and 2 m and then plot the resulting synthetic models.
End of explanation
"""


b.add_dataset('lc', times=np.linspace(0,1,101), dataset='lc01')

"""
Explanation: Influence on Light Curves (Fluxes)
Fluxes are, however, affected by distance exactly as you'd expect as inverse of distance squared.
To illustrate this, let's add an 'lc' dataset and compute synthetic fluxes at 1 and 2 m.
End of explanation
"""


b.set_value_all('ld_mode', 'manual')
b.set_value_all('ld_func', 'logarithmic')
b.set_value_all('ld_coeffs', [0.,0.])

b.set_value('distance', 1.0)

b.run_compute(model='dist1', overwrite=True)

b.set_value('distance', 2.0)

b.run_compute(model='dist2', overwrite=True)

"""
Explanation: To make things easier to compare, let's disable limb darkening
End of explanation
"""


afig, mplfig = b['lc01'].plot(show=True, legend=True)

"""
Explanation: Since we doubled the distance from 1 to 2 m, we expect the entire light curve at 2 m to be divided by 4 (note the y-scales on the plots below).
End of explanation
"""


b.add_dataset('mesh', times=[0], dataset='mesh01', columns=['intensities@lc01', 'abs_intensities@lc01'])

b.set_value('distance', 1.0)

b.run_compute(model='dist1', overwrite=True)

b.set_value('distance', 2.0)

b.run_compute(model='dist2', overwrite=True)

print("dist1 abs_intensities: ", np.nanmean(b.get_value(qualifier='abs_intensities', component='primary', dataset='lc01', model='dist1')))
print("dist2 abs_intensities: ", np.nanmean(b.get_value(qualifier='abs_intensities', component='primary', dataset='lc01', model='dist2')))

print("dist1 intensities: ", np.nanmean(b.get_value(qualifier='intensities', component='primary', dataset='lc01', model='dist1')))
print("dist2 intensities: ", np.nanmean(b.get_value(qualifier='intensities', component='primary', dataset='lc01', model='dist2')))

"""
Explanation: Note that 'pblum' is defined such that a (spherical, non-eclipsed, non-limb darkened) star with a pblum of 4pi will contribute a flux of 1.0 at 1.0 m (the default distance).
For more information, see the pblum tutorial
Influence on Meshes (Intensities)
Distance does not affect the intensities stored in the mesh (including those in relative units).  In other words, like third light, distance only scales the fluxes.
NOTE: this is different than pblums which DO affect the relative intensities.  Again, see the pblum tutorial for more details.
To see this we can run both of our distances again and look at the values of the intensities in the mesh.
End of explanation
"""


