1 package org.lcsim.recon.tracking.spacegeom;
2 /** A differential path element vector ds in Cartesian,
3 * cylindrical or spherical coordinates. It is constructed using a
4 * subclass and then elements can be fetched for any of these coordinate
5 * systems. The stored vector can also include scalar quantities.
6 * Typical applications include velocity ds/dt and direction ds/d|s|.
7 *<p>
8 * Transformations (translations, rotations, etc) are not provided.
9 * It is expected these will be carried out by external functions which
10 * return new SpacePath objects.
11 *
12 *<p>
13 * Three orthogonal coordinate systems are:
14 *<ul>
15 *<li> Cartesian: (x, y, z)
16 *<li> Cylindrical: (rxy, phi, z)
17 *<li> Spherical: (rxyz, theta, phi) .
18 *</ul>
19 * These coordinates may be obtained via the space point interface.
20 *
21 *<p>
22 * The corresponding path element vectors are:
23 *<ul>
24 *<li> Cartesian: (dx, dy, dz)
25 *<li> Cylindrical: (drxy, rxy*dphi, dz)
26 *<li> Spherical: (drxyz, rxyz*dtheta, rxy*dphi) .
27 *</ul>
28 * These elements may be accessed via the usual space vector interface
29 * (v_x(), v_y(), ...) or via the methods defined here.
30 *<p>
31 *@author Norman A. Graf
32 *@version 1.0
33 *
34 */
35 public class SpacePath extends SpacePointVector
36 {
37
38 // methods
39
40 /** Default constructor.
41 *
42 */
43 public SpacePath( )
44 {
45 super();
46 }
47
48 /** Copy onstructor from a space point.
49 * @param spt the Spacepoint to replicate
50 */
51 public SpacePath( SpacePoint spt )
52 {
53 super(spt);
54 }
55
56 /** Constructor from a space vector.
57 * @param svec the SpacePointVector from which to contruct
58 */
59 public SpacePath( SpacePointVector svec )
60 {
61 super(svec);
62 }
63
64 /**
65 * Sets the origin of the path
66 * @param p point in space
67 */
68 public void setOrigin(SpacePoint p) {
69 _x = p._x;
70 _y = p._y;
71 _z = p._z;
72 _xy = p._xy;
73 _xyz = p._xyz;
74 _phi = p._phi;
75 _theta = p._theta;
76 }
77
78 /**
79 * Sets the end point of the path
80 * @param p point in space
81 */
82 public void setEndPoint(SpacePoint p) {
83 _vx = p._x - _x;
84 _vy = p._y - _y;
85 _vz = p._z - _z;
86 }
87
88 /**
89 * Returns the origin of the path
90 * @return a new SpacePoint object at the origin
91 */
92 public SpacePoint origin() {
93 return new CartesianPoint(_x, _y, _z);
94 }
95
96 /**
97 * Returns the end point of the path
98 * @return a new SpacePoint object at the end of the path
99 */
100 public SpacePoint endPoint() {
101 return new CartesianPoint(_x+_vx, _y+_vy, _z+_vz);
102 }
103
104
105 /** Cartesian dx.
106 * @return delta x
107 */
108 public double dx( )
109 {
110 return v_x();
111 }
112
113 /** Cartesian dy.
114 * @return delta y
115 */
116 public double dy( )
117 {
118 return v_y();
119 }
120
121 /** Cartesian or cylindrical dz.
122 * @return Cartesian or cylindrical dz.
123 */
124 public double dz( )
125 {
126 return v_z();
127 }
128
129 /** Cylindrical drxy.
130 * Can be well defined at rxy=0.
131 * @return Cylindrical dradius
132 */
133 public double drxy( )
134 {
135 return v_rxy();
136 }
137
138 /** Cylindrical or spherical rxy*dphi.
139 * Can be well defined at rxy=0.
140 * @return radius*dphi (2d radius)
141 */
142 public double rxy_dphi( )
143 {
144 return v_phi();
145 }
146
147 /** Cylindrical or spherical dphi.
148 * Not well defined at rxy=0.
149 * @return dphi (not well defined at r=0)
150 */
151 public double dphi( )
152 {
153 return v_phi()/v_rxy();
154 }
155
156 /** Spherical rxyz.
157 * Can be well defined at rxyz=0.
158 * @return spherical radius
159 */
160 public double drxyz( )
161 { return v_rxyz(); }
162
163 /** Spherical rxyz*dtheta.
164 * Can be well defined at rxyz=0.
165 * @return spherical radius*dtheta
166 */
167 public double rxyz_dtheta( )
168 {
169 return v_theta();
170 }
171
172 /** Spherical dtheta.
173 * Not well defined at rxyz=0;
174 * @return Spherical dtheta.
175 */
176 public double dtheta( )
177 {
178 return v_theta()/v_rxyz();
179 }
180
181
182 /** Output stream
183 *
184 *
185 * @return String representation of the object
186 */
187 public String toString()
188 {
189 return super.toString()
190 + "SpacePath: " + "\n"
191 + " dx: " + dx() + "\n"
192 + " dy: " + dy() + "\n"
193 + " dz: " + dz() + "\n"
194 + " drxy: " + drxy() + "\n"
195 + " drxyz: " + drxyz() + "\n"
196 + " rt*dphi: " + rxy_dphi() + "\n"
197 + " r*dtheta: " + rxyz_dtheta() + "\n"
198 + "Magnitude: " + magnitude() + "\n";
199 }
200
201 }
202