From 638dbee9e2726f8227c892e81edcc19223234371 Mon Sep 17 00:00:00 2001
From: Michael Wedel <michael.wedel@psi.ch>
Date: Fri, 1 May 2015 12:07:16 +0200
Subject: [PATCH] Refs #11674. Adding 2theta - 2theta_0 to 2DHelper

---
 .../MantidSINQ/PoldiUtilities/PoldiSpectrumDomainFunction.h  | 5 +++--
 .../SINQ/src/PoldiUtilities/PoldiSpectrumDomainFunction.cpp  | 3 +++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Code/Mantid/Framework/SINQ/inc/MantidSINQ/PoldiUtilities/PoldiSpectrumDomainFunction.h b/Code/Mantid/Framework/SINQ/inc/MantidSINQ/PoldiUtilities/PoldiSpectrumDomainFunction.h
index 83022d463941..a2becbdb7a8c 100644
--- a/Code/Mantid/Framework/SINQ/inc/MantidSINQ/PoldiUtilities/PoldiSpectrumDomainFunction.h
+++ b/Code/Mantid/Framework/SINQ/inc/MantidSINQ/PoldiUtilities/PoldiSpectrumDomainFunction.h
@@ -41,8 +41,8 @@ namespace Poldi {
 struct MANTID_SINQ_DLL Poldi2DHelper {
   /// Default constructor
   Poldi2DHelper()
-      : dFractionalOffsets(), dOffsets(), domain(), values(), factors(), deltaD(),
-        minTOFN() {}
+      : dFractionalOffsets(), dOffsets(), domain(), values(), factors(),
+        deltaD(), deltaTwoTheta(), minTOFN() {}
 
   /// Transforms the chopper slit offsets for a given 2theta/distance pair.
   void setChopperSlitOffsets(double distance, double sinTheta, double deltaD,
@@ -95,6 +95,7 @@ struct MANTID_SINQ_DLL Poldi2DHelper {
   std::vector<double> factors;
 
   double deltaD;
+  double deltaTwoTheta;
   int minTOFN;
 };
 
diff --git a/Code/Mantid/Framework/SINQ/src/PoldiUtilities/PoldiSpectrumDomainFunction.cpp b/Code/Mantid/Framework/SINQ/src/PoldiUtilities/PoldiSpectrumDomainFunction.cpp
index 1eb8ca7a8a2a..b549bfbc23b7 100644
--- a/Code/Mantid/Framework/SINQ/src/PoldiUtilities/PoldiSpectrumDomainFunction.cpp
+++ b/Code/Mantid/Framework/SINQ/src/PoldiUtilities/PoldiSpectrumDomainFunction.cpp
@@ -229,6 +229,8 @@ void PoldiSpectrumDomainFunction::initializeInstrumentParameters(
   double dMin = Conversions::qToD(qLimits.second);
   double dMax = Conversions::dToQ(qLimits.first);
 
+  double centreTwoTheta = detector->twoTheta(detector->centralElement());
+
   for (int i = 0; i < static_cast<int>(detector->elementCount()); ++i) {
     double sinTheta = sin(detector->twoTheta(i) / 2.0);
     double distance =
@@ -239,6 +241,7 @@ void PoldiSpectrumDomainFunction::initializeInstrumentParameters(
     curr->setChopperSlitOffsets(distance, sinTheta, deltaD,
                                 m_chopperSlitOffsets);
     curr->setDomain(dMin, dMax, deltaD);
+    curr->deltaTwoTheta = (detector->twoTheta(i) - centreTwoTheta);
     curr->deltaD = deltaD;
     curr->minTOFN = static_cast<int>(
         Conversions::dtoTOF(dMin, distance, sinTheta) / m_deltaT);