/[PAMELA software]/eventviewer/ground/src/inter_B_inner.for
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Annotation of /eventviewer/ground/src/inter_B_inner.for

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Revision 1.1 - (hide annotations) (download)
Tue Dec 6 10:12:56 2005 UTC (19 years ago) by mocchiut
Branch point for: MAIN, EventViewer
Initial revision

1 mocchiut 1.1 *************************************************************************
2     *
3     * Subroutine inter_B_inner.f
4     *
5     * it computes the magnetic field in a chosen point x,y,z inside the
6     * magnetic cavity, using a trilinear interpolation of
7     * B field measurements (read before by means of ./read_B.f)
8     * the value is computed for two different inner maps and then averaged
9     *
10     * needs:
11     * - ../common/common_B_inner.f
12     *
13     * input: coordinates in m
14     * output: magnetic field in T
15     *
16     *************************************************************************
17    
18     subroutine inter_B_inner(x,y,z,res) !coordinates in m, magnetic field in T
19    
20     implicit double precision (a-h,o-z)
21     include './common_B_inner.for'
22    
23    
24     c------------------------------------------------------------------------
25     c
26     c local variables
27     c
28     c------------------------------------------------------------------------
29    
30     real*8 x,y,z !point of interpolation
31     real*8 res(3) !interpolated B components: res = (Bx, By, Bz)
32     real*8 res1(3),res2(3) !interpolated B components for the two maps
33    
34     integer ic !index for B components:
35     ! ic=1 ---> Bx
36     ! ic=2 ---> By
37     ! ic=3 ---> Bz
38    
39     integer cube(3) !vector of indexes identifying the cube
40     ! containing the point of interpolation
41     ! (see later...)
42    
43     real*8 xl,xh,yl,yh,zl,zh !cube vertexes coordinates
44    
45     real*8 xr,yr,zr !reduced variables (coordinates of the
46     ! point of interpolation inside the cube)
47    
48     real*8 Bp(8) !vector of values of B component
49     ! being computed, on the eight cube vertexes
50    
51    
52     c------------------------------------------------------------------------
53     c
54     c *** FIRST MAP ***
55     c
56     c------------------------------------------------------------------------
57    
58     do ic=1,3 !loops on the three B components
59    
60     c------------------------------------------------------------------------
61     c
62     c chooses the coordinates interval containing the input point
63     c
64     c------------------------------------------------------------------------
65     c e.g.:
66     c
67     c x1 x2 x3 x4 x5...
68     c |-----|-+---|-----|-----|----
69     c ~~~~~~~~x
70     c
71     c in this case the right interval is identified by indexes 2-3, so the
72     c value assigned to cube variable is 2
73    
74     cube(1)=INT((nx-1)*(x-px1min(ic))/(px1max(ic)-px1min(ic))) +1
75     cube(2)=INT((ny-1)*(y-py1min(ic))/(py1max(ic)-py1min(ic))) +1
76     cube(3)=INT((nz-1)*(z-pz1min(ic))/(pz1max(ic)-pz1min(ic))) +1
77    
78     c------------------------------------------------------------------------
79     c
80     c if the point falls beyond the extremes of the grid...
81     c
82     c------------------------------------------------------------------------
83     c
84     c ~~~~~~~~~~x1 x2 x3...
85     c - - + - - |-----|-----|----
86     c ~~~~x
87     c
88     c in the case cube = 1
89     c
90     c
91     c ...nx-2 nx-1 nx
92     c ----|-----|-----| - - - + - -
93     c ~~~~~~~~~~~~~~~~~~~~~~~~x
94     c
95     c in this case cube = nx-1
96    
97     if (cube(1).le.0) cube(1) = 1
98     if (cube(2).le.0) cube(2) = 1
99     if (cube(3).le.0) cube(3) = 1
100     if (cube(1).ge.nx) cube(1) = nx-1
101     if (cube(2).ge.ny) cube(2) = ny-1
102     if (cube(3).ge.nz) cube(3) = nz-1
103    
104    
105     c------------------------------------------------------------------------
106     c
107     c temporary variables definition for field computation
108     c
109     c------------------------------------------------------------------------
110    
111     xl = px1(cube(1),ic) !X coordinates of cube vertexes
112     xh = px1(cube(1)+1,ic)
113    
114     yl = py1(cube(2),ic) !Y coordinates of cube vertexes
115     yh = py1(cube(2)+1,ic)
116    
117     zl = pz1(cube(3),ic) !Z coordinates of cube vertexes
118     zh = pz1(cube(3)+1,ic)
119    
120     xr = (x-xl) / (xh-xl) !reduced variables
121     yr = (y-yl) / (yh-yl)
122     zr = (z-zl) / (zh-zl)
123    
124     Bp(1) = b1(cube(1) ,cube(2) ,cube(3) ,ic) !ic-th component of B
125     Bp(2) = b1(cube(1)+1,cube(2) ,cube(3) ,ic) ! on the eight cube
126     Bp(3) = b1(cube(1) ,cube(2)+1,cube(3) ,ic) ! vertexes
127     Bp(4) = b1(cube(1)+1,cube(2)+1,cube(3) ,ic)
128     Bp(5) = b1(cube(1) ,cube(2) ,cube(3)+1,ic)
129     Bp(6) = b1(cube(1)+1,cube(2) ,cube(3)+1,ic)
130     Bp(7) = b1(cube(1) ,cube(2)+1,cube(3)+1,ic)
131     Bp(8) = b1(cube(1)+1,cube(2)+1,cube(3)+1,ic)
132    
133     c------------------------------------------------------------------------
134     c
135     c computes interpolated ic-th component of B in (x,y,z)
136     c
137     c------------------------------------------------------------------------
138    
139     res1(ic) =
140     + Bp(1)*(1-xr)*(1-yr)*(1-zr) +
141     + Bp(2)*xr*(1-yr)*(1-zr) +
142     + Bp(3)*(1-xr)*yr*(1-zr) +
143     + Bp(4)*xr*yr*(1-zr) +
144     + Bp(5)*(1-xr)*(1-yr)*zr +
145     + Bp(6)*xr*(1-yr)*zr +
146     + Bp(7)*(1-xr)*yr*zr +
147     + Bp(8)*xr*yr*zr
148    
149    
150     enddo
151    
152     c------------------------------------------------------------------------
153     c
154     c *** SECOND MAP ***
155     c
156     c------------------------------------------------------------------------
157    
158     c second map is rotated by 180 degree along the Z axis. so change sign
159     c of x and y coordinates and then change sign to Bx and By components
160     c to obtain the correct result
161    
162     x=-x
163     y=-y
164    
165     do ic=1,3
166    
167     cube(1)=INT((nx-1)*(x-px2min(ic))/(px2max(ic)-px2min(ic))) +1
168     cube(2)=INT((ny-1)*(y-py2min(ic))/(py2max(ic)-py2min(ic))) +1
169     cube(3)=INT((nz-1)*(z-pz2min(ic))/(pz2max(ic)-pz2min(ic))) +1
170    
171     if (cube(1).le.0) cube(1) = 1
172     if (cube(2).le.0) cube(2) = 1
173     if (cube(3).le.0) cube(3) = 1
174     if (cube(1).ge.nx) cube(1) = nx-1
175     if (cube(2).ge.ny) cube(2) = ny-1
176     if (cube(3).ge.nz) cube(3) = nz-1
177    
178     xl = px2(cube(1),ic)
179     xh = px2(cube(1)+1,ic)
180    
181     yl = py2(cube(2),ic)
182     yh = py2(cube(2)+1,ic)
183    
184     zl = pz2(cube(3),ic)
185     zh = pz2(cube(3)+1,ic)
186    
187     xr = (x-xl) / (xh-xl)
188     yr = (y-yl) / (yh-yl)
189     zr = (z-zl) / (zh-zl)
190    
191     Bp(1) = b2(cube(1) ,cube(2) ,cube(3) ,ic)
192     Bp(2) = b2(cube(1)+1,cube(2) ,cube(3) ,ic)
193     Bp(3) = b2(cube(1) ,cube(2)+1,cube(3) ,ic)
194     Bp(4) = b2(cube(1)+1,cube(2)+1,cube(3) ,ic)
195     Bp(5) = b2(cube(1) ,cube(2) ,cube(3)+1,ic)
196     Bp(6) = b2(cube(1)+1,cube(2) ,cube(3)+1,ic)
197     Bp(7) = b2(cube(1) ,cube(2)+1,cube(3)+1,ic)
198     Bp(8) = b2(cube(1)+1,cube(2)+1,cube(3)+1,ic)
199    
200     res2(ic) =
201     + Bp(1)*(1-xr)*(1-yr)*(1-zr) +
202     + Bp(2)*xr*(1-yr)*(1-zr) +
203     + Bp(3)*(1-xr)*yr*(1-zr) +
204     + Bp(4)*xr*yr*(1-zr) +
205     + Bp(5)*(1-xr)*(1-yr)*zr +
206     + Bp(6)*xr*(1-yr)*zr +
207     + Bp(7)*(1-xr)*yr*zr +
208     + Bp(8)*xr*yr*zr
209    
210     enddo
211    
212     c change Bx and By components sign
213     res2(1)=-res2(1)
214     res2(2)=-res2(2)
215    
216     c change back the x and y coordinate signs
217     x=-x
218     y=-y
219    
220    
221     c------------------------------------------------------------------------
222     c
223     c average the two maps results
224     c
225     c------------------------------------------------------------------------
226    
227     do ic=1,3
228     res(ic)=(res1(ic)+res2(ic))/2
229     enddo
230    
231    
232     return
233     end

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