add initial manifold API for mu coordinates

manifold/sources/cbc_mu.py

@@ -5,10 +5,11 @@ References:
          Star Coalescence Using Focused Reduced Order Quadrature.” Physical Review D 102, no. 10 (November 9, 2020):
          104020. https://doi.org/10.1103/PhysRevD.102.104020.
 """
-from typing import Tuple
+from typing import Tuple, Union
 
 import numpy
 
+from manifold import coordinate
 from manifold.sources import cbc
 
 
@@ -321,3 +322,36 @@ def transform_standard_to_mu(m_1: float, m_2: float, s1_x: float, s1_y: float, s
     """
     psi = transform_standard_to_phase(m_1, m_2, s1_x, s1_y, s1_z, s2_x, s2_y, s2_z, f_ref)
     return transform_phase_to_mu(psi[0], psi[1], psi[2], u_matrix)
+
+
+################################################################################
+#                          MANIFOLD COORDINATE API                             #
+################################################################################
+
+class Mu1(coordinate.CoordinateType):
+    """Mu 1"""
+    key = 'mu1'
+
+
+class Mu2(coordinate.CoordinateType):
+    """Mu 2"""
+    key = 'mu2'
+
+
+class Mu1Mu2(cbc.CBCCoordFunc):
+    key = "mu1_mu2"
+    f_ref = 200  # TODO generalize this
+
+    TO_TYPES = (cbc.M1, cbc.M2, cbc.S1Z, cbc.S2Z)
+    FROM_TYPES = (Mu1, Mu2)
+
+    def __call__(self, c: Union[coordinate.Coordinates, coordinate.CoordsDict], inv=False):
+        if inv:
+            c = self._normalize_coorddict(c, inv=True)
+            m1, m2, s1, s2 = c[cbc.M1], c[cbc.M2], c[cbc.S1Z], c[cbc.S2Z]
+            mu = transform_standard_to_mu(m_1=m1, m_2=m2, s1_x=0, s1_y=0, s1_z=s1, s2_x=0, s2_y=0, s2_z=s2, f_ref=self.f_ref)
+            return numpy.array([mu[0], mu[1]])
+        else:  # go from mu to standard
+            # TODO why is c an array?
+            # TODO invertibility problems in paper / loss of information
+            raise NotImplementedError

manifold/sources/tests/test_cbc_mu.py

@@ -3,7 +3,9 @@
 import numpy
 from numpy import testing
 
-from manifold.sources import cbc_mu
+from manifold import coordinate
+from manifold.sources import cbc_mu, cbc
+from manifold.utilities import common
 
 
 class TestSpinVariables:
@@ -90,3 +92,17 @@ class TestCoordinateTransformations:
         testing.assert_almost_equal(numpy.array(list(res)),
                                     numpy.array([-0.0006, -0.0039, 0.0]),
                                     decimal=4)
+
+
+class TestMuManifoldAPI:
+    """Test group for mu coords manifold api agreement"""
+
+    def test_coordfunc_inverse(self):
+        """Test coordfunc inverse transformation"""
+        c = coordinate.Coordinates(10.0, 20.0, 0.5, 0.2, coord_types=[cbc.M1, cbc.M2, cbc.S1Z, cbc.S2Z])
+
+        bounds = common.bounds_from_lists(['m1', 'm2', 'S1z', 'S2z'], [0.1, 0.1, -1, -1], [400, 400, 1, 1])
+        cfunc = cbc_mu.Mu1Mu2(**bounds)
+        c_t = cfunc(c.to_dict(), inv=True)
+        testing.assert_almost_equal(c_t, numpy.array([-0.0006, -0.0039]), decimal=4)
+