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159 lines
4.3 KiB
159 lines
4.3 KiB
2 years ago
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C Copyright(C) 1999-2020 National Technology & Engineering Solutions
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C of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with
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C NTESS, the U.S. Government retains certain rights in this software.
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C
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C See packages/seacas/LICENSE for details
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SUBROUTINE PICKM3 (N, X, Y, ANGLE, M1, M2, IFIRST)
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C***********************************************************************
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C SUBROUTINE PICKM3 = DETERMINES A REASONABLE SHAPE FOR A LOGICAL
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C TRIANGLE WITH PERIMETER GIVEN IN X AND Y
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C***********************************************************************
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PARAMETER (RLARGE = 100000.)
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DIMENSION X (N), Y (N), ANGLE (N)
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DIMENSION SMANG (7), INDEX (7)
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DIMENSION ISORT (3)
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C FORM THE LIST OF SMALLEST ANGLES
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NSA = 6
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DO 100 I = 1, NSA
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SMANG (I) = 10.
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INDEX (I) = 0
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100 CONTINUE
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PI = ATAN2(0.0, -1.0)
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TWOPI = PI + PI
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AGOLD = ATAN2 (Y (1) - Y (N), X (1) - X (N))
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DO 130 J = 1, N
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C GET THE ANGLE FORMED BY THIS SET OF POINTS
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NEXT = J + 1
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IF (NEXT .GT. N) NEXT = 1
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AGNEW = ATAN2 (Y (NEXT) - Y (J) , X (NEXT) - X (J))
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DIFF = AGNEW - AGOLD
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IF (DIFF .GT. PI)DIFF = DIFF - TWOPI
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IF (DIFF .LT. - PI)DIFF = DIFF + TWOPI
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ANGLE (J) = PI - DIFF
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AGOLD = AGNEW
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C SORT THIS ANGLE AGAINST PREVIOUS ANGLES TO SEE IF IT IS ONE OF
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C THE SMALLEST
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SMANG (NSA + 1) = ANGLE (J)
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INDEX (NSA + 1) = J
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DO II = 1, NSA
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I = NSA + 1 - II
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IF (SMANG (I + 1) .GE. SMANG (I)) GO TO 120
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TEMP = SMANG (I)
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ITEMP = INDEX (I)
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SMANG (I) = SMANG (I + 1)
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INDEX (I) = INDEX (I + 1)
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SMANG (I + 1) = TEMP
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INDEX (I + 1) = ITEMP
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end do
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120 CONTINUE
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130 CONTINUE
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C DETERMINE OPTIMUM ORIGIN / SHAPE COMBINATION FOR A TRIANGLE
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ATOL = PI * 150. / 180.
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C FIND SIDE DIVISION USING 5 SMALLEST ANGLES AND CHECK CONDITION
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DO 140 I = 1, 3
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ISORT (I) = INDEX (I)
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140 CONTINUE
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DO 160 I = 1, 2
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DO 150 J = I + 1, 3
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IF (ISORT (I) .GT. ISORT (J)) THEN
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ITMP = ISORT (I)
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ISORT (I) = ISORT (J)
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ISORT (J) = ITMP
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ENDIF
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150 CONTINUE
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160 CONTINUE
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I1 = ISORT (1)
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I2 = ISORT (2)
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I3 = ISORT (3)
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MM1 = I2 - I1
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IF (MM1 .LT. 0) MM1 = N + MM1
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MM2 = I3 - I2
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IF (MM2 .LT. 0) MM2 = N + MM2
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MM3 = N - MM1 - MM2
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MAX = MAX0 (MM1, MM2, MM3)
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IF (MAX .LE. N - MAX - 2) THEN
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C ADD UP ASSIGNED ANGLES
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IFIRST = I1
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M1 = MM1
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M2 = MM2
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GBEST = ANGLE (I1) + ANGLE (I2) + ANGLE (I3)
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ELSE
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IFIRST = 1
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GBEST = RLARGE
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END IF
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C LIMIT THE SIZE OF ANY SIDE
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MMAX = (N - 2) / 2
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C GO AROUND THE PERIMETER USING THE 10 SMALLEST ANGLES AS POSSIBLE
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C STARTING POINTS, AND THEN FIND THE BEST COMBINATION OF SIDE LENGTHS
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DO 190 ISA = 1, NSA
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IF (SMANG (ISA) .LE. ATOL) THEN
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I1 = INDEX (ISA)
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SUM1 = ANGLE (I1)
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IF (SUM1 .GE. GBEST) GO TO 190
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C ASSIGN A TRIAL SECOND NODE
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DO 180 N1 = 2, MMAX
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I2 = I1 + N1
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IF (I2 .GT. N)I2 = I2 - N
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SUM2 = SUM1 + ANGLE (I2)
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IF (SUM2 .GE. GBEST) GO TO 180
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C ASSIGN A TRIAL THIRD NODE
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DO 170 N2 = 2, N - N1 - 2
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I3 = I2 + N2
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IF (I3 .GT. N)I3 = I3 - N
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GVAL = SUM2 + ANGLE (I3)
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IF (GVAL .GE. GBEST) GO TO 170
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C FIND SIDE DIVISION AND CHECK CONDITION
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MM1 = I2 - I1
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IF (MM1 .LT. 0) MM1 = N + MM1
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MM2 = I3 - I2
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IF (MM2 .LT. 0) MM2 = N + MM2
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C ... Guess by GDS, MM1 substituted for MM?
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MM3 = N - MM1 - MM2
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MAX = MAX0 (MM1, MM2, MM3)
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IF (MAX .LE. N - MAX - 2) THEN
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C ADD UP ASSIGNED ANGLES AND COMPARE TO PREVIOUS TRIALS
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IFIRST = I1
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M1 = MM1
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M2 = MM2
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GBEST = GVAL
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ENDIF
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170 CONTINUE
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180 CONTINUE
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ENDIF
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190 CONTINUE
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RETURN
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END
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