PROGRAM NNEX10
C
C Code to illustrate retrieving natural neighbor weights.
C
PARAMETER(ISLIM = 171, NUMXOUT = 21, NUMYOUT = 21,
+ IDIM=2*NUMXOUT*NUMYOUT)
C
REAL X(ISLIM+3), Y(ISLIM+3), Z(ISLIM+3)
REAL XI(NUMXOUT),YI(NUMYOUT),ZI(NUMXOUT,NUMYOUT)
C
C Array to store indices for retrieved neighbors and
C associated weights.
C
INTEGER NBRS(ISLIM)
REAL WTS(ISLIM)
C
C The data values for X and Y (defined in BLOCKDATA) are random numbers
C in the range -0.2 to 1.2. They are explicitly set here so that they
C will be uniform across all compilers.
C
COMMON /DVALUE/X,Y
C
C Define some input function values.
C
DO 5 I=1,ISLIM
Z(I) = (X(I)-0.25)**2 + (Y(I)-0.50)**2
5 CONTINUE
C
C Define an output grid.
C
XMIN = -0.2
XMAX = 1.2
XINC = (XMAX-XMIN)/(NUMXOUT-1.)
DO 20 I=1,NUMXOUT
XI(I) = XMIN+REAL(I-1) * XINC
20 CONTINUE
C
YMIN = -0.2
YMAX = 1.2
YINC = (YMAX-YMIN)/(NUMYOUT-1.)
DO 30 J=1,NUMYOUT
YI(J) = YMIN+REAL(J-1) * YINC
30 CONTINUE
C
C Enter single point mode.
C
CALL NNPNTINITS(ISLIM,X,Y,Z)
C
C Calculate the interpolated values at the desired points.
C
DO 40 I=1,21
DO 50 J=1,21
CALL NNPNTS(XI(I),YI(J),ZI(I,J))
C
C Get the indices for the neighbors and the associated weights.
C
CALL NNGETWTS(NUMW,NBRS,WTS,X(ISLIM+1), Y(ISLIM+1),
+ Z(ISLIM+1))
C
C Calculated the interpolated function value at (XI(I),YI(J))
C using the retrieved neighbors and weights and compare this
C with the value returned from NNPNTS.
C
ZP = 0.
DO 13 L=1,NUMW
ZP = ZP+WTS(L)*Z(NBRS(L))
13 CONTINUE
DIFF = (ZP-ZI(I,J))/ZP
IF (DIFF .GT. 0.000001) THEN
WRITE(6,512) I,J,ZP,ZI(I,J)
ENDIF
512 FORMAT(2I5,2F15.8)
50 CONTINUE
40 CONTINUE
C
C Test one extrapolation point.
C
CALL NNPNTS(-0.17,-0.17,ZX)
CALL NNGETWTS(NUMW,NBRS,WTS,X(ISLIM+1),Y(ISLIM+1),Z(ISLIM+1))
ZP = 0.
DO 15 L=1,NUMW
ZP = ZP+WTS(L)*Z(NBRS(L))
15 CONTINUE
DIFF = (ZP-ZX)/ZP
IF (DIFF .GT. 0.000001) THEN
WRITE(6,512) I,J,ZP,ZX
ENDIF
C
C Exit single point mode.
C
CALL NNPNTEND()
STOP
END
C
BLOCKDATA DATAV
COMMON /DVALUE/X,Y
DIMENSION X(174),Y(174)
C
DATA (X(L),L=1,171)/
+ 1.16, 0.47, 0.29, 0.72, 0.52, 1.12, 0.33, 0.20, 0.30,
+ 0.78, 0.92, 0.52, 0.44, 0.22, -0.10, 0.11, 0.59, 1.13,
+ 0.68, 1.11, 0.93, 0.29, 0.74, 0.43, 0.87, 0.87, -0.10,
+ 0.26, 0.85, 0.00, -0.02, 1.01, -0.12, 0.65, 0.39, 0.96,
+ 0.39, 0.38, 0.94, -0.03, -0.17, 0.00, 0.03, 0.67, -0.06,
+ 0.82, -0.03, 1.08, 0.37, 1.02, -0.11, -0.13, 1.03, 0.61,
+ 0.26, 0.18, 0.62, 0.42, 1.03, 0.72, 0.97, 0.08, 1.18,
+ 0.00, 0.69, 0.10, 0.80, 0.06, 0.82, 0.20, 0.46, 0.37,
+ 1.16, 0.93, 1.09, 0.96, 1.00, 0.80, 0.01, 0.12, 1.01,
+ 0.48, 0.79, 0.04, 0.42, 0.48, -0.18, 1.16, 0.85, 0.97,
+ 0.14, 0.40, 0.78, 1.12, 1.19, 0.68, 0.65, 0.41, 0.90,
+ 0.84, -0.11, -0.01, -0.02, -0.10, 1.04, 0.58, 0.61, 0.12,
+ -0.02, -0.03, 0.27, 1.17, 1.02, 0.16, -0.17, 1.03, 0.13,
+ 0.04, -0.03, 0.15, 0.00, -0.01, 0.91, 1.20, 0.54, -0.14,
+ 1.03, 0.93, 0.42, 0.36, -0.10, 0.57, 0.22, 0.74, 1.15,
+ 0.40, 0.82, 0.96, 1.09, 0.42, 1.13, 0.24, 0.51, 0.60,
+ 0.06, 0.38, 0.15, 0.59, 0.76, 1.16, 0.02, 0.86, 1.14,
+ 0.37, 0.38, 0.26, 0.26, 0.07, 0.87, 0.90, 0.83, 0.09,
+ 0.03, 0.56, -0.19, 0.51, 1.07, -0.13, 0.99, 0.84, 0.22/
DATA (Y(L),L=1,171)/
+ -0.11, 1.07, 1.11, -0.17, 0.08, 0.09, 0.91, 0.17, -0.02,
+ 0.83, 1.08, 0.87, 0.46, 0.66, 0.50, -0.14, 0.78, 1.08,
+ 0.65, 0.00, 1.03, 0.06, 0.69, -0.16, 0.02, 0.59, 0.19,
+ 0.54, 0.68, 0.95, 0.30, 0.77, 0.94, 0.76, 0.56, 0.12,
+ 0.05, -0.07, 1.01, 0.61, 1.04, -0.07, 0.46, 1.07, 0.87,
+ 0.11, 0.63, 0.06, 0.53, 0.95, 0.78, 0.48, 0.45, 0.77,
+ 0.78, 0.29, 0.38, 0.85, -0.10, 1.17, 0.35, 1.14, -0.04,
+ 0.34, -0.18, 0.78, 0.17, 0.63, 0.88, -0.12, 0.58, -0.12,
+ 1.00, 0.99, 0.45, 0.86, -0.15, 0.97, 0.99, 0.90, 0.42,
+ 0.61, 0.74, 0.41, 0.44, 1.08, 1.06, 1.18, 0.89, 0.74,
+ 0.74, -0.06, 0.00, 0.99, 0.03, 1.00, -0.04, 0.24, 0.65,
+ 0.12, 0.13, -0.09, -0.05, 1.03, 1.07, -0.02, 1.18, 0.19,
+ 0.03, -0.03, 0.86, 1.12, 0.38, 0.72, -0.20, -0.08, -0.18,
+ 0.32, 0.13, -0.19, 0.93, 0.81, 0.31, 1.09, -0.03, 1.01,
+ -0.17, 0.84, -0.11, 0.45, 0.18, 0.23, 0.81, 0.39, 1.09,
+ -0.05, 0.58, 0.53, 0.96, 0.43, 0.48, 0.96, -0.03, 1.13,
+ 1.16, 0.16, 1.15, 0.57, 0.13, 0.71, 0.35, 1.04, 0.62,
+ 1.03, 0.98, 0.31, 0.70, 0.97, 0.87, 1.14, 0.08, 1.19,
+ 0.88, 1.00, 0.51, 0.03, 0.17, 1.01, 0.44, 0.17, -0.11/
C
END
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