From 3c94a733efa86b7af4824734121d70b4c4ee5ef5 Mon Sep 17 00:00:00 2001
From: Sam Shaner <shaner@mit.edu>
Date: Fri, 29 Jul 2016 15:36:58 -0400
Subject: [PATCH] cleaned up chi equations in python API and added new MGXS to
 documentation

---
 docs/source/pythonapi/index.rst |  3 +++
 openmc/mgxs/mgxs.py             | 20 ++++++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/docs/source/pythonapi/index.rst b/docs/source/pythonapi/index.rst
index 36f161b3c..df50eee0b 100644
--- a/docs/source/pythonapi/index.rst
+++ b/docs/source/pythonapi/index.rst
@@ -269,13 +269,16 @@ Multi-group Cross Sections
     openmc.mgxs.AbsorptionXS
     openmc.mgxs.CaptureXS
     openmc.mgxs.Chi
+    openmc.mgxs.ChiPrompt
     openmc.mgxs.FissionXS
+    openmc.mgxs.InverseVelocity
     openmc.mgxs.KappaFissionXS
     openmc.mgxs.MultiplicityMatrixXS
     openmc.mgxs.NuFissionXS
     openmc.mgxs.NuFissionMatrixXS
     openmc.mgxs.NuScatterXS
     openmc.mgxs.NuScatterMatrixXS
+    openmc.mgxs.PromptNuFissionXS
     openmc.mgxs.ScatterXS
     openmc.mgxs.ScatterMatrixXS
     openmc.mgxs.TotalXS
diff --git a/openmc/mgxs/mgxs.py b/openmc/mgxs/mgxs.py
index c359379f4..36d5a00be 100644
--- a/openmc/mgxs/mgxs.py
+++ b/openmc/mgxs/mgxs.py
@@ -4209,14 +4209,14 @@ class Chi(MGXS):
 
     .. math::
 
-       \langle \nu\sigma_{f,\rightarrow g} \phi \rangle &= \int_{r \in V} dr
+       \langle \nu\sigma_{f,g' \rightarrow g} \phi \rangle &= \int_{r \in V} dr
        \int_{4\pi} d\Omega' \int_0^\infty dE' \int_{E_g}^{E_{g-1}} dE \; \chi(E)
        \nu\sigma_f (r, E') \psi(r, E', \Omega')\\
        \langle \nu\sigma_f \phi \rangle &= \int_{r \in V} dr \int_{4\pi}
        d\Omega' \int_0^\infty dE' \int_0^\infty dE \; \chi(E) \nu\sigma_f (r,
        E') \psi(r, E', \Omega') \\
-       \chi_g &= \frac{\langle \nu\sigma_{f,\rightarrow g} \phi \rangle}{\langle
-       \nu\sigma_f \phi \rangle}
+       \chi_g &= \frac{\langle \nu\sigma_{f,g' \rightarrow g} \phi \rangle}
+       {\langle \nu\sigma_f \phi \rangle}
 
     Parameters
     ----------
@@ -4692,14 +4692,14 @@ class ChiPrompt(Chi):
 
     .. math::
 
-       \langle \nu\sigma_{f,\rightarrow g}^p \phi \rangle &= \int_{r \in V} dr
-       \int_{4\pi} d\Omega' \int_0^\infty dE' \int_{E_g}^{E_{g-1}} dE \; \chi(E)
-       \nu\sigma_f^p (r, E') \psi(r, E', \Omega')\\
-       \langle \nu\sigma_f^p \phi \rangle &= \int_{r \in V} dr \int_{4\pi}
-       d\Omega' \int_0^\infty dE' \int_0^\infty dE \; \chi(E) \nu\sigma_f^p (r,
+       \langle \nu^p \sigma_{f,g' \rightarrow g} \phi \rangle &= \int_{r \in V}
+       dr \int_{4\pi} d\Omega' \int_0^\infty dE' \int_{E_g}^{E_{g-1}} dE \;
+       \chi(E) \nu^p \sigma_f (r, E') \psi(r, E', \Omega')\\
+       \langle \nu^p \sigma_f \phi \rangle &= \int_{r \in V} dr \int_{4\pi}
+       d\Omega' \int_0^\infty dE' \int_0^\infty dE \; \chi(E) \nu^p \sigma_f (r,
        E') \psi(r, E', \Omega') \\
-       \chi_g^p &= \frac{\langle \nu\sigma_{f,\rightarrow g}^p \phi \rangle}{\langle
-       \nu\sigma_f^p \phi \rangle}
+       \chi_g^p &= \frac{\langle \nu^p \sigma_{f,g' \rightarrow g} \phi \rangle}
+       {\langle \nu^p \sigma_f \phi \rangle}
 
     Parameters
     ----------