/[PAMELA software]/gpamela/gpfield/inter_B_inner.F
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Annotation of /gpamela/gpfield/inter_B_inner.F

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Revision 3.1 - (hide annotations) (download)
Tue Dec 6 01:07:28 2005 UTC (18 years, 11 months ago) by cafagna
Branch: MAIN
CVS Tags: v4r4, v4r5, v4r6, v4r7, v4r8, v4r9, v4r14, v4r12, v4r13, v4r10, v4r11, HEAD
Adding new magnetic field routines

1 cafagna 3.1 *************************************************************************
2     *
3     * Subroutine inter_B_inner.f (from tracker software analysis)
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     IMPLICIT DOUBLE PRECISION (A-H,O-Z)
20     #include "gpfield.inc"
21    
22     c------------------------------------------------------------------------
23     c
24     c local variables
25     c
26     c------------------------------------------------------------------------
27    
28     real*8 x,y,z !point of interpolation
29     real*8 res(3) !interpolated B components: res = (Bx, By, Bz)
30     real*8 res1(3),res2(3) !interpolated B components for the two maps
31    
32     integer ic !index for B components:
33     ! ic=1 ---> Bx
34     ! ic=2 ---> By
35     ! ic=3 ---> Bz
36    
37     integer cube(3) !vector of indexes identifying the cube
38     ! containing the point of interpolation
39     ! (see later...)
40    
41     real*8 xl,xh,yl,yh,zl,zh !cube vertexes coordinates
42    
43     real*8 xr,yr,zr !reduced variables (coordinates of the
44     ! point of interpolation inside the cube)
45    
46     real*8 Bp(8) !vector of values of B component
47     ! being computed, on the eight cube vertexes
48    
49    
50     c------------------------------------------------------------------------
51     c
52     c *** FIRST MAP ***
53     c
54     c------------------------------------------------------------------------
55    
56     do ic=1,3 !loops on the three B components
57    
58     c------------------------------------------------------------------------
59     c
60     c chooses the coordinates interval containing the input point
61     c
62     c------------------------------------------------------------------------
63     c e.g.:
64     c
65     c x1 x2 x3 x4 x5...
66     c |-----|-+---|-----|-----|----
67     c ~~~~~~~~x
68     c
69     c in this case the right interval is identified by indexes 2-3, so the
70     c value assigned to cube variable is 2
71    
72     cube(1)=INT((nx-1)*(x-px1min(ic))/(px1max(ic)-px1min(ic))) +1
73     cube(2)=INT((ny-1)*(y-py1min(ic))/(py1max(ic)-py1min(ic))) +1
74     cube(3)=INT((nz-1)*(z-pz1min(ic))/(pz1max(ic)-pz1min(ic))) +1
75    
76     c------------------------------------------------------------------------
77     c
78     c if the point falls beyond the extremes of the grid...
79     c
80     c------------------------------------------------------------------------
81     c
82     c ~~~~~~~~~~x1 x2 x3...
83     c - - + - - |-----|-----|----
84     c ~~~~x
85     c
86     c in the case cube = 1
87     c
88     c
89     c ...nx-2 nx-1 nx
90     c ----|-----|-----| - - - + - -
91     c ~~~~~~~~~~~~~~~~~~~~~~~~x
92     c
93     c in this case cube = nx-1
94    
95     if (cube(1).le.0) cube(1) = 1
96     if (cube(2).le.0) cube(2) = 1
97     if (cube(3).le.0) cube(3) = 1
98     if (cube(1).ge.nx) cube(1) = nx-1
99     if (cube(2).ge.ny) cube(2) = ny-1
100     if (cube(3).ge.nz) cube(3) = nz-1
101    
102    
103     c------------------------------------------------------------------------
104     c
105     c temporary variables definition for field computation
106     c
107     c------------------------------------------------------------------------
108    
109     xl = px1(cube(1),ic) !X coordinates of cube vertexes
110     xh = px1(cube(1)+1,ic)
111    
112     yl = py1(cube(2),ic) !Y coordinates of cube vertexes
113     yh = py1(cube(2)+1,ic)
114    
115     zl = pz1(cube(3),ic) !Z coordinates of cube vertexes
116     zh = pz1(cube(3)+1,ic)
117    
118     xr = (x-xl) / (xh-xl) !reduced variables
119     yr = (y-yl) / (yh-yl)
120     zr = (z-zl) / (zh-zl)
121    
122     Bp(1) = b1(cube(1) ,cube(2) ,cube(3) ,ic) !ic-th component of B
123     Bp(2) = b1(cube(1)+1,cube(2) ,cube(3) ,ic) ! on the eight cube
124     Bp(3) = b1(cube(1) ,cube(2)+1,cube(3) ,ic) ! vertexes
125     Bp(4) = b1(cube(1)+1,cube(2)+1,cube(3) ,ic)
126     Bp(5) = b1(cube(1) ,cube(2) ,cube(3)+1,ic)
127     Bp(6) = b1(cube(1)+1,cube(2) ,cube(3)+1,ic)
128     Bp(7) = b1(cube(1) ,cube(2)+1,cube(3)+1,ic)
129     Bp(8) = b1(cube(1)+1,cube(2)+1,cube(3)+1,ic)
130    
131     c------------------------------------------------------------------------
132     c
133     c computes interpolated ic-th component of B in (x,y,z)
134     c
135     c------------------------------------------------------------------------
136    
137     res1(ic) =
138     + Bp(1)*(1-xr)*(1-yr)*(1-zr) +
139     + Bp(2)*xr*(1-yr)*(1-zr) +
140     + Bp(3)*(1-xr)*yr*(1-zr) +
141     + Bp(4)*xr*yr*(1-zr) +
142     + Bp(5)*(1-xr)*(1-yr)*zr +
143     + Bp(6)*xr*(1-yr)*zr +
144     + Bp(7)*(1-xr)*yr*zr +
145     + Bp(8)*xr*yr*zr
146    
147    
148     enddo
149    
150     c------------------------------------------------------------------------
151     c
152     c *** SECOND MAP ***
153     c
154     c------------------------------------------------------------------------
155    
156     c second map is rotated by 180 degree along the Z axis. so change sign
157     c of x and y coordinates and then change sign to Bx and By components
158     c to obtain the correct result
159    
160     x=-x
161     y=-y
162    
163     do ic=1,3
164    
165     cube(1)=INT((nx-1)*(x-px2min(ic))/(px2max(ic)-px2min(ic))) +1
166     cube(2)=INT((ny-1)*(y-py2min(ic))/(py2max(ic)-py2min(ic))) +1
167     cube(3)=INT((nz-1)*(z-pz2min(ic))/(pz2max(ic)-pz2min(ic))) +1
168    
169     if (cube(1).le.0) cube(1) = 1
170     if (cube(2).le.0) cube(2) = 1
171     if (cube(3).le.0) cube(3) = 1
172     if (cube(1).ge.nx) cube(1) = nx-1
173     if (cube(2).ge.ny) cube(2) = ny-1
174     if (cube(3).ge.nz) cube(3) = nz-1
175    
176     xl = px2(cube(1),ic)
177     xh = px2(cube(1)+1,ic)
178    
179     yl = py2(cube(2),ic)
180     yh = py2(cube(2)+1,ic)
181    
182     zl = pz2(cube(3),ic)
183     zh = pz2(cube(3)+1,ic)
184    
185     xr = (x-xl) / (xh-xl)
186     yr = (y-yl) / (yh-yl)
187     zr = (z-zl) / (zh-zl)
188    
189     Bp(1) = b2(cube(1) ,cube(2) ,cube(3) ,ic)
190     Bp(2) = b2(cube(1)+1,cube(2) ,cube(3) ,ic)
191     Bp(3) = b2(cube(1) ,cube(2)+1,cube(3) ,ic)
192     Bp(4) = b2(cube(1)+1,cube(2)+1,cube(3) ,ic)
193     Bp(5) = b2(cube(1) ,cube(2) ,cube(3)+1,ic)
194     Bp(6) = b2(cube(1)+1,cube(2) ,cube(3)+1,ic)
195     Bp(7) = b2(cube(1) ,cube(2)+1,cube(3)+1,ic)
196     Bp(8) = b2(cube(1)+1,cube(2)+1,cube(3)+1,ic)
197    
198     res2(ic) =
199     + Bp(1)*(1-xr)*(1-yr)*(1-zr) +
200     + Bp(2)*xr*(1-yr)*(1-zr) +
201     + Bp(3)*(1-xr)*yr*(1-zr) +
202     + Bp(4)*xr*yr*(1-zr) +
203     + Bp(5)*(1-xr)*(1-yr)*zr +
204     + Bp(6)*xr*(1-yr)*zr +
205     + Bp(7)*(1-xr)*yr*zr +
206     + Bp(8)*xr*yr*zr
207    
208     enddo
209    
210     c change Bx and By components sign
211     res2(1)=-res2(1)
212     res2(2)=-res2(2)
213    
214     c change back the x and y coordinate signs
215     x=-x
216     y=-y
217    
218    
219     c------------------------------------------------------------------------
220     c
221     c average the two maps results
222     c
223     c------------------------------------------------------------------------
224    
225     do ic=1,3
226     res(ic)=(res1(ic)+res2(ic))/2
227     enddo
228    
229    
230     return
231     end

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