From 0394aa72a6fc9eeca911da1af98360cd4bea4fa9 Mon Sep 17 00:00:00 2001
From: Colm Talbot <colm.talbot@ligo.org>
Date: Mon, 1 Oct 2018 18:39:58 -0500
Subject: [PATCH] add aligned spin prior
---
CHANGELOG.md | 1 +
test/prior_test.py | 4 ++--
tupak/gw/prior.py | 40 +++++++++++++++++++++++++++++++++++++++-
3 files changed, 42 insertions(+), 3 deletions(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9da7f48f..9172cf23 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@ Changes currently on master, but not under a tag.
- Hyperparameter estimation now enables the user to provide the single event evidences
- Add nested samples to nestle output
- Prior and child classes now implement the \_\_eq\_\_ magic method for comparisons
+- Add AlignedSpin gw prior
### Changes
- Fix construct_cbc_derived_parameters
diff --git a/test/prior_test.py b/test/prior_test.py
index 3b22b6c6..89047308 100644
--- a/test/prior_test.py
+++ b/test/prior_test.py
@@ -7,7 +7,6 @@ import os
import shutil
from collections import OrderedDict
-
class TestPriorInstantiationWithoutOptionalPriors(unittest.TestCase):
def setUp(self):
@@ -152,7 +151,8 @@ class TestPriorClasses(unittest.TestCase):
tupak.core.prior.Cauchy(name='test', unit='unit', alpha=0, beta=1),
tupak.core.prior.Lorentzian(name='test', unit='unit', alpha=0, beta=1),
tupak.core.prior.Gamma(name='test', unit='unit', k=1, theta=1),
- tupak.core.prior.ChiSquared(name='test', unit='unit', nu=2)
+ tupak.core.prior.ChiSquared(name='test', unit='unit', nu=2),
+ tupak.gw.prior.AlignedSpin(name='test', unit='unit')
]
def test_minimum_rescaling(self):
diff --git a/tupak/gw/prior.py b/tupak/gw/prior.py
index e876b254..d45f2a7e 100644
--- a/tupak/gw/prior.py
+++ b/tupak/gw/prior.py
@@ -1,5 +1,6 @@
import os
-from ..core.prior import PriorSet, FromFile, Prior, DeltaFunction, Gaussian
+from ..core.prior import (PriorSet, Uniform, FromFile, Prior, DeltaFunction,
+ Gaussian, Interped)
from ..core.utils import logger
import numpy as np
from scipy.interpolate import UnivariateSpline
@@ -26,6 +27,43 @@ class UniformComovingVolume(FromFile):
latex_label=latex_label, unit='Mpc')
+class AlignedSpin(Interped):
+
+ def __init__(self, a_prior=Uniform(0, 1), z_prior=Uniform(-1, 1),
+ name=None, latex_label=None, unit=None):
+ """
+ Prior distribution for the aligned (z) component of the spin.
+
+ This takes prior distributions for the magnitude and cosine of the tilt
+ and forms a compound prior.
+
+ This is useful when using aligned-spin only waveform approximants.
+
+ This is an extension of e.g., (A7) of https://arxiv.org/abs/1805.10457.
+
+ Parameters
+ ----------
+ a_prior: Prior
+ Prior distribution for spin magnitude
+ z_prior: Prior
+ Prior distribution for cosine spin tilt
+ name: see superclass
+ latex_label: see superclass
+ unit: see superclass
+ """
+ self.a_prior = a_prior
+ self.z_prior = z_prior
+ chi_min = min(a_prior.maximum * z_prior.minimum,
+ a_prior.minimum * z_prior.maximum)
+ chi_max = a_prior.maximum * z_prior.maximum
+ xx = np.linspace(chi_min, chi_max, 800)
+ aas = np.linspace(a_prior.minimum, a_prior.maximum, 1000)
+ yy = [np.trapz(np.nan_to_num(a_prior.prob(aas) / aas *
+ z_prior.prob(x / aas)), aas) for x in xx]
+ Interped.__init__(self, xx=xx, yy=yy, name=name,
+ latex_label=latex_label, unit=unit)
+
+
class BBHPriorSet(PriorSet):
def __init__(self, dictionary=None, filename=None):
""" Initialises a Prior set for Binary Black holes
--
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