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 #ifndef _TkRADIAL_STRIP_TOPOLOGY_H_
 #define _TkRADIAL_STRIP_TOPOLOGY_H_
 
 #include "Geometry/CommonTopologies/interface/RadialStripTopology.h"
 
 /**
  * \class TkRadialStripTopology
  * A StripTopology in which the component strips subtend a constant
  * angular width, and, if projected, intersect at a point.
  *
  * \author Tim Cox
  *
  * WARNING! Wherever 'float strip' is used the units of 'strip' are angular
  * widths of each strip. The range is from 0.0 at the extreme edge of the
  * 'first' strip at one edge of the detector, to nstrip*angular width
  * at the other edge. <BR>
  * The centre of the first strip is at strip = 0.5 <BR>
  * The centre of the last strip is at strip = 0.5 + (nstrip-1) <BR>
  * This is for consistency with CommonDet usage of 'float strip' (but
  * where units are strip pitch rather than strip angular width.)<BR>
  *
  * WARNING! If the mid-point along local y of the plane of strips does not correspond
  * to the local coordinate origin, set the final ctor argument appropriately. <BR>
  *
  * this version is optimized for tracker and is FINAL
  */
 
 class TkRadialStripTopology final : public RadialStripTopology {
 public:
   /** 
    * Constructor from:
    *    \param ns number of strips
    *    \param aw angular width of a strip
    *    \param dh detector height (usually 2 x apothem of TrapezoidalPlaneBounds)
    *    \param r radial distance from symmetry centre of detector to the point at which 
    *    the outer edges of the two extreme strips (projected) intersect.
    *    \param yAx orientation of local y axis: 1 means pointing from the smaller side of
    *    the module to the larger side (along apothem), and -1 means in the 
    *    opposite direction, i.e. from the larger side along the apothem to the 
    *    smaller side. Default value is 1. 
    *    \param yMid local y offset if mid-point of detector (strip plane) does not coincide with local origin.
    *    This decouples the extent of strip plane from the boundary of the detector in which the RST is embedded.
    */
   TkRadialStripTopology(int ns, float aw, float dh, float r, int yAx = 1, float yMid = 0.);
 
   /** 
    * Destructor
    */
   ~TkRadialStripTopology() override {}
 
   // =========================================================
   // StripTopology interface - implement pure methods
   // =========================================================
 
   /** 
    * LocalPoint on x axis for given 'strip'
    * 'strip' is a float in units of the strip (angular) width
    */
   LocalPoint localPosition(float strip) const override;
 
   /** 
    * LocalPoint for a given MeasurementPoint <BR>
    * What's a MeasurementPoint?  <BR>
    * In analogy with that used with TrapezoidalStripTopology objects,
    * a MeasurementPoint is a 2-dim object.<BR>
    * The first dimension measures the
    * angular position wrt central line of symmetry of detector,
    * in units of strip (angular) widths (range 0 to total angle subtended
    * by a detector).<BR>
    * The second dimension measures
    * the fractional position along the strip (range -0.5 to +0.5).<BR>
    * BEWARE! The components are not Cartesian.<BR>
    */
   LocalPoint localPosition(const MeasurementPoint&) const override;
 
   /** 
    * LocalError for a pure strip measurement, where 'strip'
    * is the (float) position (a 'phi' angle wrt y axis) and
    * stripErr2 is the sigma-squared. Both quantities are expressed in
    * units of theAngularWidth of a strip.
    */
   LocalError localError(float strip, float stripErr2) const override;
 
   /** 
    * LocalError for a given MeasurementPoint with known MeasurementError.
    * This may be used in Kalman filtering and hence must allow possible
    * correlations between the components.
    */
   LocalError localError(const MeasurementPoint&, const MeasurementError&) const override;
 
   /** 
    * Strip in which a given LocalPoint lies. This is a float which
    * represents the fractional strip position within the detector.<BR>
    * Returns zero if the LocalPoint falls at the extreme low edge of the
    * detector or BELOW, and float(nstrips) if it falls at the extreme high
    * edge or ABOVE.
    */
   float strip(const LocalPoint&) const override;
 
   // the number of strip span by the segment between the two points..
   float coveredStrips(const LocalPoint& lp1, const LocalPoint& lp2) const override;
 
   /** 
    * Pitch (strip width) at a given LocalPoint. <BR>
    * BEWARE: are you sure you really want to call this for a RadialStripTopology?
    */
   float localPitch(const LocalPoint&) const override;
 
   /** 
    * Angle between strip and symmetry axis (=local y axis)
    * for given strip. <BR>
    * This is like a phi angle but measured clockwise from y axis 
    * rather than counter clockwise from x axis.
    * Note that 'strip' is a float with a continuous range from 0 to 
    * float(nstrips) to cover the whole detector, and the centres of
    * strips correspond to half-integer values 0.5, 1.5, ..., nstrips-0.5
    * whereas values 1, 2, ... nstrips correspond to the upper phi edges of
    * the strips.
    */
   float stripAngle(float strip) const override {
     return yAxisOrientation() * (phiOfOneEdge() + strip * angularWidth());
   }
 
   /** 
    * Total number of strips 
    */
   int nstrips() const override { return theNumberOfStrips; }
 
   /** 
    * Height of detector (= length of long symmetry axis of the plane of strips).
    */
   float stripLength() const override { return theDetHeight; }
 
   /** 
    * Length of a strip passing through a given LocalPpoint
    */
   float localStripLength(const LocalPoint&) const override;
 
   // =========================================================
   // Topology interface (not already implemented for
   // StripTopology interface)
   // =========================================================
 
   MeasurementPoint measurementPosition(const LocalPoint&) const override;
 
   MeasurementError measurementError(const LocalPoint&, const LocalError&) const override;
 
   /** 
    * Channel number corresponding to a given LocalPoint.<BR>
    * This is effectively an integer version of strip(), with range 0 to
    * nstrips-1.  <BR>
    * LocalPoints outside the detector strip plane will be considered
    * as contributing to the edge channels 0 or nstrips-1.
    */
   int channel(const LocalPoint&) const override;
 
   // =========================================================
   // RadialStripTopology interface itself
   // =========================================================
 
   /** 
    * Angular width of a each strip
    */
   float angularWidth() const override { return theAngularWidth; }
 
   /** 
    * Phi pitch of each strip (= angular width!)
    */
   float phiPitch(void) const override { return angularWidth(); }
 
   /** 
    * Length of long symmetry axis of plane of strips
    */
   float detHeight() const override { return theDetHeight; }
 
   /** 
    * y extent of strip plane
    */
   float yExtentOfStripPlane() const override { return theDetHeight; }  // same as detHeight()
 
   /** 
    * Distance from the intersection of the projections of
    * the extreme edges of the two extreme strips to the symmetry
    * centre of the plane of strips. 
    */
   float centreToIntersection() const override { return theCentreToIntersection; }
 
   /** 
    * (y) distance from intersection of the projections of the strips
    * to the local coordinate origin. Same as centreToIntersection()
    * if symmetry centre of strip plane coincides with local origin.
    */
   float originToIntersection() const override { return (theCentreToIntersection - yCentre); }
 
   /**
    * Convenience function to access azimuthal angle of extreme edge of first strip 
    * measured relative to long symmetry axis of the plane of strips. <BR>
    *
    * WARNING! This angle is measured clockwise from the local y axis 
    * which means it is in the conventional azimuthal phi plane, 
    * but azimuth is of course measured from local x axis not y. 
    * The range of this angle is
    *  -(full angle)/2 to +(full angle)/2. <BR>
    * where (full angle) = nstrips() * angularWidth(). <BR>
    *
    */
   float phiOfOneEdge() const override { return thePhiOfOneEdge; }
 
   /**
    * Local x where centre of strip intersects input local y <BR>
    * 'strip' should be in range 1 to nstrips() <BR>
    */
   float xOfStrip(int strip, float y) const override;
 
   /**
    * Nearest strip to given LocalPoint
    */
   int nearestStrip(const LocalPoint&) const override;
 
   /** 
    * y axis orientation, 1 means detector width increases with local y
    */
   float yAxisOrientation() const override { return theYAxisOrientation; }
 
   /**
    * Offset in local y between midpoint of detector (strip plane) extent and local origin
    */
   float yCentreOfStripPlane() const override { return yCentre; }
 
   /**
    * Distance in local y from a hit to the point of intersection of projected strips
    */
   float yDistanceToIntersection(float y) const override;
 
 private:
   int theNumberOfStrips;          // total no. of strips in plane of strips
   float theAngularWidth;          // angle subtended by each strip = phi pitch
   float theAWidthInverse;         // inverse of above
   float theTanAW;                 // its tangent
   float theDetHeight;             // length of long symmetry axis = twice the apothem of the enclosing trapezoid
   float theCentreToIntersection;  // distance centre of detector face to intersection of edge strips (projected)
   float thePhiOfOneEdge;          // local 'phi' of one edge of plane of strips (I choose it negative!)
   float theTanOfOneEdge;          // the positive tangent of the above...
   float theYAxisOrientation;      // 1 means y axis going from smaller to larger side, -1 means opposite direction
   float yCentre;  // Non-zero if offset in local y between midpoint of detector (strip plane) extent and local origin.
   double theRadialSigma;  // radial sigma^2( uniform prob density along strip)
 };
 
 #endif

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