MINICERN/mathlib/gen/d/elpahy.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.1  1996/04/01 15:02:18  mclareni
   6 * Mathlib gen
   7 *
   8 *
   9 #include "gen/pilot.h"
  10       SUBROUTINE ELPAHY(F,IDIM1,IDIM2,DX,DY,COEFS,IBX,BWEST,BEAST,
  11      1JBY,BSOUTH,BNORTH)
  12       DIMENSION COEFS(3)
  13       DIMENSION F(IDIM1,IDIM2)
  14       DIMENSION BWEST(IDIM2),BEAST(IDIM2),BNORTH(IDIM1),BSOUTH(IDIM1)
  15 C------------------------------------------
  16 C   KIND OF EQUATION AND COEFFICIENTS     I
  17 C------------------------------------------
  18 C   IKIND=1-ELLIPTIC ,=2-PARABOLIC ,=3-HYPERBOLIC
  19 C
  20 C   DX2+AD*DY2+BD*DY+CD*Y=SOURCE
  21 C
  22       AD=COEFS(1)
  23       BD=COEFS(2)
  24       CD=COEFS(3)
  25       IF(AD) 510,511,512
  26  510  IKIND=3
  27       GO TO 513
  28  511  IKIND=2
  29       GO TO 513
  30  512  IKIND=1
  31  513  CONTINUE
  32 C------------------------------------------
  33 C   MESH DIVISION AND CELL SIZE           I
  34 C------------------------------------------
  35 C   IDIM1 DIVISIONS ALONG THE X-DIRECTION
  36 C   IDIM2 DIVISIONS ALONG THE Y-DIRECTION
  37 C   DX = CELL SIZE ALOND X
  38 C   DY = CELL SIZE ALONG Y
  39 C
  40       RAT=DX/DY
  41       RAT2=RAT*RAT
  42       DX2=DX*DX
  43       AT=RAT2*AD
  44       BT=RAT*DX*BD
  45       CT=DX2*CD
  46       DO 1 I=1,IDIM1
  47       DO 1 J=1,IDIM2
  48  1    F(I,J)=DX2*F(I,J)
  49 C------------------------------------------
  50 C   BOUNDARY CONDITIONS                   I
  51 C------------------------------------------
  52 C   ALONG THE WEST AND EAST BOUNDARIES
  53 C   IBX=1-PERIODIC ,=2-DERIVATIVE ,=3-VALUE ,=4-VALUE+DERIVATIVE
  54 C
  55 C   ALONG THE SOUTH AND NORTH BOUNDARIES
  56 C   JBY=1   VALUE=BSOUTH(I) ,VALUE=BNORTH(I)
  57 C   JBY=2   DERIVATIVE=BSOUTH(I) ,DERIVATIVE=BNORTH(I)
  58 C   JBY=3   VALUE=BSOUTH(I) ,DERIVATIVE=BNORTH(I)
  59 C   JBY=4   DERIVATIVE=BSOUTH(I) ,VALUE=BNORTH(I)
  60 C
  61       GO TO (520,521,522,523) ,JBY
  62  520  ALFAS=1.
  63       BETAS=0.
  64       ALFAN=1.
  65       BETAN=0.
  66       GO TO 524
  67  521  ALFAS=0.
  68       BETAS=1.
  69       ALFAN=0.
  70       BETAN=1.
  71       GO TO 524
  72  522  ALFAS=1.
  73       BETAS=0.
  74       ALFAN=0.
  75       BETAN=1.
  76       GO TO 524
  77  523  ALFAS=0.
  78       BETAS=1.
  79       ALFAN=1.
  80       BETAN=0.
  81  524  CONTINUE
  82 C
  83 C   THIS SUBROUTINE MODIFIES THE SOURCE TERM
  84 C   AT EACH END OF THE X-RANGE ACCORDING
  85 C   TO THE TYPE OF BOUNDARY CONDITIONS
  86 C   CHOSEN ALONG THAT DIRECTION
  87 C
  88       CALL NEWRO(IDIM1,IDIM2,IBX,DX,F,BWEST,BEAST,BSOUTH,BNORTH)
  89 C
  90 C   THIS SUBROUTINE PERFORMS THE APPROPRIATE
  91 C   FOURIER ANALYSIS OF THE SOURCE TERM
  92 C   ALONG THE X-DIRECTION USING FAST FOURIER
  93 C   TRANSFORM TECHNIQUES
  94 C
  95       CALL ELANAL(IDIM1,IDIM2,IBX,F,BWEST,BEAST,BSOUTH,BNORTH)
  96 C
  97 C   THIS SUBROUTINE SOLVES THE TWO-POINTS
  98 C   OR THREE-POINTS RECURRENCE FORMULA ALONG
  99 C   THE SECOND DIMENSION FOR EITHER ONE OF
 100 C   THE ELLIPTIC,PARABOLIC OR HYPERBOLIC TYPE
 101 C   OF EQUATIONS
 102 C
 103       CALL ESOLVE(IDIM1,IDIM2,AT,BT,CT,DY,IBX,ALFAS,BETAS,ALFAN,BETAN,
 104      1F,IKIND)
 105 C
 106 C   THIS SUBROUTINE PERFORMS THE APPROPRIATE
 107 C   FOURIER SYNTHESIS OF THE UNKNOWWN FUNCTION
 108 C   ALONG THE X-DIRECTION USING FAST FOURIER
 109 C   TRANSFORM TECHNIQUES
 110 C
 111       CALL SYNT(IDIM1,IDIM2,IBX,F)
 112 C
 113 C
 114       GO TO (100,110,120,130),IBX
 115  100  DO 101 J=1,IDIM2
 116  101  F(IDIM1,J)=F(1,J)
 117       GO TO 110
 118  120  DO 121 J=1,IDIM2
 119       F(1,J)=BWEST(J)
 120  121  F(IDIM1,J)=BEAST(J)
 121       GO TO 110
 122  130  DO 131 J=1,IDIM2
 123  131  F(1,J)=BWEST(J)
 124  110  RETURN
 125       END