summaryrefslogtreecommitdiff
path: root/Trivac/src/PN3DXX.f
blob: 5f519133ccf26318789900fd3d5de928b4718744 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
*DECK PN3DXX
      SUBROUTINE PN3DXX(NBMIX,IELEM,ICOL,NEL,NLF,NVD,NAN,LL4F,LL4X,
     1 SIGT,SIGTI,MAT,VOL,XX,YY,ZZ,KN,QFR,MUX,IPBBX,LC,R,V,BBX,TTF,
     2 AX,C11X)
*
*-----------------------------------------------------------------------
*
*Purpose:
* Assembly of system matrices for a Thomas-Raviart (dual) finite element
* method in 3-D simplified PN approximation. Note: system matrices
* should be initialized by the calling program.
*
*Copyright:
* Copyright (C) 2005 Ecole Polytechnique de Montreal
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version
*
*Author(s): A. Hebert
*
*Parameters: input
* NBMIX   number of mixtures.
* IELEM   degree of the Lagrangian finite elements: =1 (linear);
*         =2 (parabolic); =3 (cubic).
* ICOL    type of quadrature: =1 (analytical integration);
*         =2 (Gauss-Lobatto); =3 (Gauss-Legendre).
* NEL     total number of finite elements.
* NLF     number of Legendre orders for the flux (even number).
* NVD     type of void boundary condition if NLF>0 and ICOL=3.
* NAN     number of Legendre orders for the cross sections.
* LL4F    number of flux components.
* LL4X    number of X-directed currents.
* LL4Y    number of Y-directed currents.
* LL4Z    number of Z-directed currents.
* SIGT    total minus self-scattering macroscopic cross sections.
*         SIGT(:,NAN) generally contains the total cross section only.
* SIGTI   inverse macroscopic cross sections ordered by mixture.
*         SIGTI(:,NAN) generally contains the inverse total cross
*         section only.
* MAT     mixture index assigned to each element.
* VOL     volume of each element.
* XX      X-directed mesh spacings.
* YY      Y-directed mesh spacings.
* ZZ      Z-directed mesh spacings.
* KN      element-ordered unknown list.
* QFR     element-ordered boundary conditions.
* MUX     X-directed compressed storage mode indices.
* MUY     Y-directed compressed storage mode indices.
* MUZ     Z-directed compressed storage mode indices.
* IPBBX   X-directed perdue storage indices.
* IPBBY   Y-directed perdue storage indices.
* IPBBZ   Z-directed perdue storage indices.
* LC      order of the unit matrices.
* R       unit matrix.
* V       unit matrix.
* BBX     X-directed flux-current matrices.
* BBY     Y-directed flux-current matrices.
* BBZ     Z-directed flux-current matrices.
*
*Parameters: output
* TTF     flux-flux matrices.
* AX      X-directed main current-current matrices. Dimensionned to
*         MUX(LL4X)*NLF/2.
* AY      Y-directed main current-current matrices. Dimensionned to
*         MUY(LL4Y)*NLF/2.
* AZ      Z-directed main current-current matrices. Dimensionned to
*         MUZ(LL4Z)*NLF/2.
* C11X    X-directed main current-current matrices to be factorized.
*         Dimensionned to MUX(LL4X)*NLF/2.
* C11Y    Y-directed main current-current matrices to be factorized.
*         Dimensionned to MUY(LL4Y)*NLF/2.
* C11Z    Z-directed main current-current matrices to be factorized.
*         Dimensionned to MUZ(LL4Z)*NLF/2.
*
*Reference(s):
* J.J. Lautard, D. Schneider, A.M. Baudron, "Mixed Dual Methods for
* Neutronic Reactor Core Calculations in the CRONOS System," Proc.
* Int. Conf. on Mathematics and Computation, Reactor Physics and
* Environmental Analysis in Nuclear Applications, Madrid, Spain,
* September 27-30, 1999.
*
*-----------------------------------------------------------------------
*
*----
*  SUBROUTINE ARGUMENTS
*----
      INTEGER NBMIX,IELEM,ICOL,NEL,NLF,NVD,NAN,LL4F,LL4X,MAT(NEL),
     1 KN(NEL*(1+6*IELEM**2)),MUX(LL4X),IPBBX(2*IELEM,LL4X),LC
      REAL SIGT(NBMIX,NAN),SIGTI(NBMIX,NAN),VOL(NEL),XX(NEL),YY(NEL),
     1 ZZ(NEL),QFR(6*NEL),R(LC,LC),V(LC,LC-1),BBX(2*IELEM,LL4X),
     2 TTF(LL4F*NLF/2),AX(*),C11X(*)
*----
*  LOCAL VARIABLES
*----
      REAL QQ(5,5)
*----
*  X-ORIENTED COUPLINGS
*----
      ZMARS=0.0
      IF(ICOL.EQ.3) THEN
         IF(NVD.EQ.0) THEN
            NZMAR=NLF+1
         ELSE IF(NVD.EQ.1) THEN
            NZMAR=NLF
         ELSE IF(NVD.EQ.2) THEN
            NZMAR=65
         ENDIF
      ELSE
         NZMAR=65
      ENDIF
      DO 25 I0=1,IELEM
      DO 20 J0=1,IELEM
      FFF=0.0
      DO 10 K0=2,IELEM
      FFF=FFF+V(K0,I0)*V(K0,J0)/R(K0,K0)
   10 CONTINUE
      IF(ABS(FFF).LE.1.0E-6) FFF=0.0
      QQ(I0,J0)=FFF
   20 CONTINUE
   25 CONTINUE
      MUMAX=MUX(LL4X)
      DO 170 IL=0,NLF-1
      IF(MOD(IL,2).EQ.1) ZMARS=PNMAR2(NZMAR,IL,IL)
      FACT=REAL(2*IL+1)
*----
*  ASSEMBLY OF THE X-ORIENTED COEFFICIENT MATRICES AT ORDER IL.
*----
      NUM1=0
      NUM2=0
      DO 120 IE=1,NEL
      IBM=MAT(IE)
      IF(IBM.EQ.0) GO TO 120
      VOL0=VOL(IE)
      IF(VOL0.EQ.0.0) GO TO 110
      DX=XX(IE)
      DY=YY(IE)
      DZ=ZZ(IE)
      GARS=SIGT(IBM,MIN(IL+1,NAN))
      IF(MOD(IL,2).EQ.0) THEN
*        EVEN PARITY EQUATION.
         DO 32 K3=0,IELEM-1
         DO 31 K2=0,IELEM-1
         DO 30 K1=0,IELEM-1
         KEY=(IL/2)*LL4F+KN(NUM1+1)+(K3*IELEM+K2)*IELEM+K1
         TTF(KEY)=TTF(KEY)+FACT*VOL0*GARS
   30    CONTINUE
   31    CONTINUE
   32    CONTINUE
      ELSE
         GARSI=SIGTI(IBM,MIN(IL+1,NAN))
         DO 105 K3=0,IELEM-1
         DO 100 K2=0,IELEM-1
*        PARTIAL INVERSION OF THE ODD PARITY EQUATION. MODIFICATION OF
*        THE EVEN PARITY EQUATION.
         DO 40 K1=0,IELEM-1
         JND1=KN(NUM1+1)+(K3*IELEM+K2)*IELEM+K1
         KEY=((IL-1)/2)*LL4F+JND1
         TTF(KEY)=TTF(KEY)+(REAL(IL)**2)*VOL0*QQ(K1+1,K1+1)*GARSI/(FACT*
     1   DX*DX)
         IF(IL.LE.NLF-3) THEN
            KEY=((IL+2)/2)*LL4F+JND1
            TTF(KEY)=TTF(KEY)+(REAL(IL+1)**2)*VOL0*QQ(K1+1,K1+1)*GARSI/
     1      (FACT*DX*DX)
         ENDIF
         KEY=((IL-1)/2)*LL4F+JND1
         TTF(KEY)=TTF(KEY)+(REAL(IL)**2)*VOL0*QQ(K2+1,K2+1)*GARSI/
     1   (FACT*DY*DY)
         IF(IL.LE.NLF-3) THEN
            KEY=((IL+2)/2)*LL4F+JND1
            TTF(KEY)=TTF(KEY)+(REAL(IL+1)**2)*VOL0*QQ(K2+1,K2+1)*GARSI/
     1      (FACT*DY*DY)
         ENDIF
         KEY=((IL-1)/2)*LL4F+JND1
         TTF(KEY)=TTF(KEY)+(REAL(IL)**2)*VOL0*QQ(K3+1,K3+1)*GARSI/
     1   (FACT*DZ*DZ)
         IF(IL.LE.NLF-3) THEN
            KEY=((IL+2)/2)*LL4F+JND1
            TTF(KEY)=TTF(KEY)+(REAL(IL+1)**2)*VOL0*QQ(K3+1,K3+1)*GARSI/
     1      (FACT*DZ*DZ)
         ENDIF
   40    CONTINUE
*
*        ODD PARITY EQUATION.
         DO 55 IC=1,2
         IF(IC.EQ.1) IIC=1
         IF(IC.EQ.2) IIC=IELEM+1
         KN1=KN(NUM1+2+(IC-1)*IELEM**2+K3*IELEM+K2)
         IND1=ABS(KN1)-LL4F
         S1=REAL(SIGN(1,KN1))
         DO 50 JC=1,2
         IF(JC.EQ.1) JJC=1
         IF(JC.EQ.2) JJC=IELEM+1
         KN2=KN(NUM1+2+(JC-1)*IELEM**2+K3*IELEM+K2)
         IND2=ABS(KN2)-LL4F
         IF((KN1.NE.0).AND.(KN2.NE.0).AND.(IND1.GE.IND2)) THEN
            S2=REAL(SIGN(1,KN2))
            KEY=((IL-1)/2)*MUMAX+MUX(IND1)-IND1+IND2
            AX(KEY)=AX(KEY)-S1*S2*FACT*R(IIC,JJC)*VOL0*GARS
         ENDIF
   50    CONTINUE
   55    CONTINUE
*
         KN1=KN(NUM1+2+K3*IELEM+K2)
         KN2=KN(NUM1+2+IELEM**2+K3*IELEM+K2)
         IND1=ABS(KN1)-LL4F
         IND2=ABS(KN2)-LL4F
         IF((QFR(NUM2+1).NE.0.0).AND.(KN1.NE.0)) THEN
            KEY=((IL-1)/2)*MUMAX+MUX(IND1)
            AX(KEY)=AX(KEY)-0.5*FACT*QFR(NUM2+1)*ZMARS
         ENDIF
         IF((QFR(NUM2+2).NE.0.0).AND.(KN2.NE.0)) THEN
            KEY=((IL-1)/2)*MUMAX+MUX(IND2)
            AX(KEY)=AX(KEY)-0.5*FACT*QFR(NUM2+2)*ZMARS
         ENDIF
  100    CONTINUE
  105    CONTINUE
      ENDIF
  110 NUM1=NUM1+1+6*IELEM**2
      NUM2=NUM2+6
  120 CONTINUE
*
      IF(MOD(IL,2).EQ.1) THEN
         DO 130 I0=1,MUMAX
         C11X(((IL-1)/2)*MUMAX+I0)=-AX(((IL-1)/2)*MUMAX+I0)
  130    CONTINUE
         MUIM1=0
         DO 160 I=1,LL4X
         MUI=MUX(I)
         DO 150 J=I-(MUI-MUIM1)+1,I
         KEY=((IL-1)/2)*MUMAX+(MUI-I+J)
         DO 145 I0=1,2*IELEM
         II=IPBBX(I0,I)
         IF(II.EQ.0) GO TO 150
         DO 140 J0=1,2*IELEM
         JJ=IPBBX(J0,J)
         IF(II.EQ.JJ) C11X(KEY)=C11X(KEY)+REAL(IL**2)*BBX(I0,I)*
     1   BBX(J0,J)/TTF(((IL-1)/2)*LL4F+II)
  140    CONTINUE
  145    CONTINUE
  150    CONTINUE
         MUIM1=MUI
  160    CONTINUE
      ENDIF
  170 CONTINUE
      RETURN
      END
*
      SUBROUTINE PN3DXY(NBMIX,IELEM,ICOL,NEL,NLF,NVD,NAN,LL4F,LL4X,LL4Y,
     1 SIGT,MAT,VOL,YY,KN,QFR,MUY,IPBBY,LC,R,BBY,TTF,AY,C11Y)
*----
*  SUBROUTINE ARGUMENTS
*----
      INTEGER NBMIX,IELEM,ICOL,NEL,NLF,NVD,NAN,LL4F,LL4X,LL4Y,MAT(NEL),
     1 KN(NEL*(1+6*IELEM**2)),MUY(LL4Y),IPBBY(2*IELEM,LL4Y),LC
      REAL SIGT(NBMIX,NAN),VOL(NEL),YY(NEL),QFR(6*NEL),R(LC,LC),
     1 BBY(2*IELEM,LL4Y),TTF(LL4F*NLF/2),AY(*),C11Y(*)
*----
*  Y-ORIENTED COUPLINGS
*----
      ZMARS=0.0
      IF(ICOL.EQ.3) THEN
         IF(NVD.EQ.0) THEN
            NZMAR=NLF+1
         ELSE IF(NVD.EQ.1) THEN
            NZMAR=NLF
         ELSE IF(NVD.EQ.2) THEN
            NZMAR=65
         ENDIF
      ELSE
         NZMAR=65
      ENDIF
      MUMAX=MUY(LL4Y)
      DO 320 IL=1,NLF-1,2
      ZMARS=PNMAR2(NZMAR,IL,IL)
      FACT=REAL(2*IL+1)
*----
*  ASSEMBLY OF THE Y-ORIENTED COEFFICIENT MATRICES AT ODD ORDER IL.
*----
      NUM1=0
      NUM2=0
      DO 270 IE=1,NEL
      IBM=MAT(IE)
      IF(IBM.EQ.0) GO TO 270
      VOL0=VOL(IE)
      IF(VOL0.EQ.0.0) GO TO 260
      DY=YY(IE)
      GARS=SIGT(IBM,MIN(IL+1,NAN))
*
      DO 255 K3=0,IELEM-1
      DO 250 K1=0,IELEM-1
      DO 205 IC=3,4
      IF(IC.EQ.3) IIC=1
      IF(IC.EQ.4) IIC=IELEM+1
      KN1=KN(NUM1+2+(IC-1)*IELEM**2+K3*IELEM+K1)
      IND1=ABS(KN1)-LL4F-LL4X
      S1=REAL(SIGN(1,KN1))
      DO 200 JC=3,4
      IF(JC.EQ.3) JJC=1
      IF(JC.EQ.4) JJC=IELEM+1
      KN2=KN(NUM1+2+(JC-1)*IELEM**2+K3*IELEM+K1)
      IND2=ABS(KN2)-LL4F-LL4X
      IF((KN1.NE.0).AND.(KN2.NE.0).AND.(IND1.GE.IND2)) THEN
         S2=REAL(SIGN(1,KN2))
         KEY=((IL-1)/2)*MUMAX+MUY(IND1)-IND1+IND2
         AY(KEY)=AY(KEY)-S1*S2*FACT*R(IIC,JJC)*VOL0*GARS
      ENDIF
  200 CONTINUE
  205 CONTINUE
*
      KN1=KN(NUM1+2+2*IELEM**2+K3*IELEM+K1)
      KN2=KN(NUM1+2+3*IELEM**2+K3*IELEM+K1)
      IND1=ABS(KN1)-LL4F-LL4X
      IND2=ABS(KN2)-LL4F-LL4X
      IF((QFR(NUM2+3).NE.0.0).AND.(KN1.NE.0)) THEN
         KEY=((IL-1)/2)*MUMAX+MUY(IND1)
         AY(KEY)=AY(KEY)-0.5*FACT*QFR(NUM2+3)*ZMARS
      ENDIF
      IF((QFR(NUM2+4).NE.0.0).AND.(KN2.NE.0)) THEN
         KEY=((IL-1)/2)*MUMAX+MUY(IND2)
         AY(KEY)=AY(KEY)-0.5*FACT*QFR(NUM2+4)*ZMARS
      ENDIF
  250 CONTINUE
  255 CONTINUE
  260 NUM1=NUM1+1+6*IELEM**2
      NUM2=NUM2+6
  270 CONTINUE
*
      DO 280 I0=1,MUMAX
      C11Y(((IL-1)/2)*MUMAX+I0)=-AY(((IL-1)/2)*MUMAX+I0)
  280 CONTINUE
      MUIM1=0
      DO 310 I=1,LL4Y
      MUI=MUY(I)
      DO 300 J=I-(MUI-MUIM1)+1,I
      KEY=((IL-1)/2)*MUMAX+(MUI-I+J)
      DO 295 I0=1,2*IELEM
      II=IPBBY(I0,I)
      IF(II.EQ.0) GO TO 300
      DO 290 J0=1,2*IELEM
      JJ=IPBBY(J0,J)
      IF(II.EQ.JJ) C11Y(KEY)=C11Y(KEY)+REAL(IL**2)*BBY(I0,I)*BBY(J0,J)/
     1 TTF(((IL-1)/2)*LL4F+II)
  290 CONTINUE
  295 CONTINUE
  300 CONTINUE
      MUIM1=MUI
  310 CONTINUE
  320 CONTINUE
      RETURN
      END
*
      SUBROUTINE PN3DXZ(NBMIX,IELEM,ICOL,NEL,NLF,NVD,NAN,LL4F,LL4X,LL4Y,
     1 LL4Z,SIGT,MAT,VOL,ZZ,KN,QFR,MUZ,IPBBZ,LC,R,BBZ,TTF,AZ,C11Z)
*----
*  SUBROUTINE ARGUMENTS
*----
      INTEGER NBMIX,IELEM,ICOL,NEL,NLF,NVD,NAN,LL4F,LL4X,LL4Y,LL4Z,
     1 MAT(NEL),KN(NEL*(1+6*IELEM**2)),MUZ(LL4Z),IPBBZ(2*IELEM,LL4Z),LC
      REAL SIGT(NBMIX,NAN),VOL(NEL),ZZ(NEL),QFR(6*NEL),R(LC,LC),
     1 BBZ(2*IELEM,LL4Z),TTF(LL4F*NLF/2),AZ(*),C11Z(*)
*----
*  Z-ORIENTED COUPLINGS
*----
      ZMARS=0.0
      IF(ICOL.EQ.3) THEN
         IF(NVD.EQ.0) THEN
            NZMAR=NLF+1
         ELSE IF(NVD.EQ.1) THEN
            NZMAR=NLF
         ELSE IF(NVD.EQ.2) THEN
            NZMAR=65
         ENDIF
      ELSE
         NZMAR=65
      ENDIF
      MUMAX=MUZ(LL4Z)
      DO 470 IL=1,NLF-1,2
      ZMARS=PNMAR2(NZMAR,IL,IL)
      FACT=REAL(2*IL+1)
*----
*  ASSEMBLY OF THE Z-ORIENTED COEFFICIENT MATRICES AT ORDER IL.
*----
      NUM1=0
      NUM2=0
      DO 420 IE=1,NEL
      IBM=MAT(IE)
      IF(IBM.EQ.0) GO TO 420
      VOL0=VOL(IE)
      IF(VOL0.EQ.0.0) GO TO 410
      DZ=ZZ(IE)
      GARS=SIGT(IBM,MIN(IL+1,NAN))
*
      DO 405 K2=0,IELEM-1
      DO 400 K1=0,IELEM-1
      DO 355 IC=5,6
      IF(IC.EQ.5) IIC=1
      IF(IC.EQ.6) IIC=IELEM+1
      KN1=KN(NUM1+2+(IC-1)*IELEM**2+K2*IELEM+K1)
      IND1=ABS(KN1)-LL4F-LL4X-LL4Y
      S1=REAL(SIGN(1,KN1))
      DO 350 JC=5,6
      IF(JC.EQ.5) JJC=1
      IF(JC.EQ.6) JJC=IELEM+1
      KN2=KN(NUM1+2+(JC-1)*IELEM**2+K2*IELEM+K1)
      IND2=ABS(KN2)-LL4F-LL4X-LL4Y
      IF((KN1.NE.0).AND.(KN2.NE.0).AND.(IND1.GE.IND2)) THEN
         S2=REAL(SIGN(1,KN2))
         KEY=((IL-1)/2)*MUMAX+MUZ(IND1)-IND1+IND2
         AZ(KEY)=AZ(KEY)-S1*S2*FACT*R(IIC,JJC)*VOL0*GARS
      ENDIF
  350 CONTINUE
  355 CONTINUE
*
      KN1=KN(NUM1+2+4*IELEM**2+K2*IELEM+K1)
      KN2=KN(NUM1+2+5*IELEM**2+K2*IELEM+K1)
      IND1=ABS(KN1)-LL4F-LL4X-LL4Y
      IND2=ABS(KN2)-LL4F-LL4X-LL4Y
      IF((QFR(NUM2+5).NE.0.0).AND.(KN1.NE.0)) THEN
         KEY=((IL-1)/2)*MUMAX+MUZ(IND1)
         AZ(KEY)=AZ(KEY)-0.5*FACT*QFR(NUM2+5)*ZMARS
      ENDIF
      IF((QFR(NUM2+6).NE.0.0).AND.(KN2.NE.0)) THEN
         KEY=((IL-1)/2)*MUMAX+MUZ(IND2)
         AZ(KEY)=AZ(KEY)-0.5*FACT*QFR(NUM2+6)*ZMARS
      ENDIF
  400 CONTINUE
  405 CONTINUE
  410 NUM1=NUM1+1+6*IELEM**2
      NUM2=NUM2+6
  420 CONTINUE
*
      DO 430 I0=1,MUMAX
      C11Z(((IL-1)/2)*MUMAX+I0)=-AZ(((IL-1)/2)*MUMAX+I0)
  430 CONTINUE
      MUIM1=0
      DO 460 I=1,LL4Z
      MUI=MUZ(I)
      DO 450 J=I-(MUI-MUIM1)+1,I
      KEY=((IL-1)/2)*MUMAX+(MUI-I+J)
      DO 445 I0=1,2*IELEM
      II=IPBBZ(I0,I)
      IF(II.EQ.0) GO TO 450
      DO 440 J0=1,2*IELEM
      JJ=IPBBZ(J0,J)
      IF(II.EQ.JJ) C11Z(KEY)=C11Z(KEY)+REAL(IL**2)*BBZ(I0,I)*BBZ(J0,J)/
     1 TTF(((IL-1)/2)*LL4F+II)
  440 CONTINUE
  445 CONTINUE
  450 CONTINUE
      MUIM1=MUI
  460 CONTINUE
  470 CONTINUE
      RETURN
      END