Cloned SEACAS for EXODUS library with extra build files for internal package management.
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C Copyright(C) 1999-2020 National Technology & Engineering Solutions
C of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with
C NTESS, the U.S. Government retains certain rights in this software.
C
C See packages/seacas/LICENSE for details
C========================================================================
SUBROUTINE EXTS(IGLND,INVCN,MAXLN,NXGLND,INVLEN,XA,YA,ZA,
& CNTRA,SOLEA,SOLENA,ITT,iblk)
C
C************************************************************************
C
C Subroutine EXTS sets up the matrix and vectors for a least squares
C linear interpolation/extrapolation of element variable data to the
C nodes for a 4-node quad element. In the special case of data from
C only 3 elements, the result is not least squares fit but a
C triangularization.
C
C Calls subroutines FRGE & BS
C
C Called by SELTN3
C
C************************************************************************
C
C IGLND INT The global node number being processed
C INVCN INT Inverse connectivity (1:maxln,1:numnda)
C MAXLN INT The maximum number of elements connected to any node
C NXGLND INT The local node used to get elements from INVCN
C INVLEN INT The number of elements connected to NXGLND
C XA,etc REAL Vectors containing nodal coordinates
C CNTRA REAL Array containing the coordinates of the element
C centroids (1:3)
C SOLEA REAL The element variables
C SOLENA REAL Element variables at nodes
C number with the global mesh node number (1:numnda)
C ITT INT truth table
C iblk INT element block being processed (not ID)
C INTND INT The global node number associated with IGLND
C S REAL The coefficient matrix for the least squares fit
C L INT Dummy vector - used in FRGE and BS
C X REAL The solution vector - used in BS
C G REAL Dummy vector - used in FRGE
C F REAL The load vector for the least squares fit
C
C************************************************************************
C
include 'aexds1.blk'
include 'amesh.blk'
include 'ebbyeb.blk'
include 'tapes.blk'
C
DIMENSION INVCN(MAXLN,*),XA(*),YA(*),ZA(*)
DIMENSION CNTRA(NUMEBA,*),SOLEA(NUMEBA,*)
DIMENSION SOLENA(NODESA,NVAREL), ITT(NVAREL,*)
DIMENSION IFRST(3), RLENTH(8), XLC(8), YLC(8)
C DIMENSION ZLC(8)
DOUBLE PRECISION S(3,3),G(3),F(3),X(3)
INTEGER L(3)
C
C************************************************************************
C
C Zero matrix
C
DO I = 1,3
IFRST(I) = I
DO J = 1,3
S(I,J) = 0.D+00
end do
end do
c
c find distance from interpolation point to element centroids
c
DO I = 1, INVLEN
A = XA(IGLND) - CNTRA(INVCN(I,NXGLND),1)
B = YA(IGLND) - CNTRA(INVCN(I,NXGLND),2)
C = ZA(IGLND) - CNTRA(INVCN(I,NXGLND),3)
RLENTH(I) = SQRT(A*A + B*B + C*C)
end do
C
C find the three closest element centroids
C
IF (INVLEN .EQ. 3) THEN
DO I = 1, 2
IF (RLENTH(I) .GT. RLENTH(I+1))THEN
ITEMP = IFRST(I)
IFRST(I) = IFRST(I+1)
IFRST(I+1) = ITEMP
END IF
end do
IF (RLENTH(1) .GT. RLENTH(2))THEN
ITEMP = IFRST(1)
IFRST(1) = IFRST(2)
IFRST(2) = ITEMP
END IF
C
ELSE
DO I = 2, INVLEN
IF (RLENTH(I) .LT. RLENTH(IFRST(1))) IFRST(1) = I
end do
IFRST(2) = 1
IF (IFRST(1) .EQ. 1) IFRST(2) = 2
DO I = IFRST(2), INVLEN
IF (I .EQ. IFRST(1))GO TO 50
IF (RLENTH(I) .LT. RLENTH(IFRST(2)))IFRST(2) = I
50 CONTINUE
end do
IFRST(3) = 1
IF (IFRST(1) .EQ. 1 .OR. IFRST(2) .EQ. 1) IFRST(3)=2
IF (IFRST(1) .EQ. IFRST(3) .OR. IFRST(2) .EQ. IFRST(3))
& IFRST(3)=3
DO I = IFRST(3), INVLEN
IF (I .EQ. IFRST(1))GO TO 60
IF (I .EQ. IFRST(2))GO TO 60
IF (RLENTH(I) .LT. RLENTH(IFRST(3))) IFRST(3) = I
60 CONTINUE
end do
END IF
C
C use three closest element centroids to define a plane
C establish coordinate system on this plane centered on
C interpolation point
C
A11 = CNTRA(INVCN(IFRST(2),NXGLND),1) -
& CNTRA(INVCN(IFRST(1),NXGLND),1)
A12 = CNTRA(INVCN(IFRST(2),NXGLND),2) -
& CNTRA(INVCN(IFRST(1),NXGLND),2)
A13 = CNTRA(INVCN(IFRST(2),NXGLND),3) -
& CNTRA(INVCN(IFRST(1),NXGLND),3)
RLN = SQRT(A11*A11 + A12*A12 + A13*A13)
A11 = A11/RLN
A12 = A12/RLN
A13 = A13/RLN
C
A31 = (CNTRA(INVCN(IFRST(2),NXGLND),2) -
& CNTRA(INVCN(IFRST(1),NXGLND),2))
& * (CNTRA(INVCN(IFRST(3),NXGLND),3) -
& CNTRA(INVCN(IFRST(1),NXGLND),3))
& - (CNTRA(INVCN(IFRST(2),NXGLND),3) -
& CNTRA(INVCN(IFRST(1),NXGLND),3))
& * (CNTRA(INVCN(IFRST(3),NXGLND),2) -
& CNTRA(INVCN(IFRST(1),NXGLND),2))
A32 = (CNTRA(INVCN(IFRST(2),NXGLND),3) -
& CNTRA(INVCN(IFRST(1),NXGLND),3))
& * (CNTRA(INVCN(IFRST(3),NXGLND),1) -
& CNTRA(INVCN(IFRST(1),NXGLND),1))
& - (CNTRA(INVCN(IFRST(2),NXGLND),1) -
& CNTRA(INVCN(IFRST(1),NXGLND),1))
& * (CNTRA(INVCN(IFRST(3),NXGLND),3) -
& CNTRA(INVCN(IFRST(1),NXGLND),3))
A33 = (CNTRA(INVCN(IFRST(2),NXGLND),1) -
& CNTRA(INVCN(IFRST(1),NXGLND),1))
& * (CNTRA(INVCN(IFRST(3),NXGLND),2) -
& CNTRA(INVCN(IFRST(1),NXGLND),2))
& - (CNTRA(INVCN(IFRST(2),NXGLND),2) -
& CNTRA(INVCN(IFRST(1),NXGLND),2))
& * (CNTRA(INVCN(IFRST(3),NXGLND),1) -
& CNTRA(INVCN(IFRST(1),NXGLND),1))
RLN = SQRT(A31*A31 + A32*A32 + A33*A33)
A31 = A31/RLN
A32 = A32/RLN
A33 = A33/RLN
C
A21 = A32*A13 - A33*A12
A22 = A11*A33 - A31*A13
A23 = A31*A12 - A11*A32
C
DO I = 1, INVLEN
XLC(I) = A11 * (CNTRA(INVCN(I,NXGLND),1) - XA(IGLND))
& + A12 * (CNTRA(INVCN(I,NXGLND),2) - YA(IGLND))
& + A13 * (CNTRA(INVCN(I,NXGLND),3) - ZA(IGLND))
YLC(I) = A21 * (CNTRA(INVCN(I,NXGLND),1) - XA(IGLND))
& + A22 * (CNTRA(INVCN(I,NXGLND),2) - YA(IGLND))
& + A23 * (CNTRA(INVCN(I,NXGLND),3) - ZA(IGLND))
end do
C
C
C Set up matrix for linear fit
C
S(1,1) = INVLEN
DO I = 1, INVLEN
S(1,2) = S(1,2) + DBLE(XLC(I))
S(1,3) = S(1,3) + DBLE(YLC(I))
S(2,2) = S(2,2) + DBLE(XLC(I) * XLC(I))
S(2,3) = S(2,3) + DBLE(YLC(I) * XLC(I))
S(3,3) = S(3,3) + DBLE(YLC(I) * YLC(I))
end do
S(2,1) = S(1,2)
S(3,1) = S(1,3)
S(3,2) = S(2,3)
C
C Forward Gauss elimination (Kincaid pg. 220) (double precision)
C
CALL FRGE(3,S,L,G)
C
C Set up load vectors - number of element variables
C
DO IVAR = 1, NVAREL
IF (ITT(IVAR,iblk) .EQ. 0)GO TO 90
F(1) = 0.D+00
F(2) = 0.D+00
F(3) = 0.D+00
DO I = 1, INVLEN
F(1) = F(1) + DBLE(SOLEA(INVCN(I,NXGLND),IVAR))
F(2) = F(2) + DBLE(SOLEA(INVCN(I,NXGLND),IVAR) * XLC(I))
F(3) = F(3) + DBLE(SOLEA(INVCN(I,NXGLND),IVAR) * YLC(I))
end do
C
C Back substitution (Kincaid pg. 223) (double precision)
C
CALL BS(3,S,F,L,X)
C
C Fill in nodal element value array (SOLENA)
C Note: X and Y distances in S and F are centered on node being
C interpolated, thus X and Y are zero in the eq.
C Value = X(1) + X(2) * X + X(3) * Y
C
SOLENA(IGLND,IVAR) = SNGL(X(1))
90 CONTINUE
end do
RETURN
END