SUBROUTINE SPLINE(S,X,Y,N,IN,T,IL,VL,IU,VU,E,U) 00000100 C X,Y ARRAY OF IND. & DEPEN. VAR.,S THE ARGUMENT TO BE INTERPOLATED 00000200 C T THE INTERPOLATED VALUE,N THE DIMENSION OF (X,Y) 00000300 C IN=1 DETERMINES SPLINE FUNC,IN=2 INTERPOLATES SPLINE FNC 00000400 C IL,IU=1 PARABOLIC RUNOUT CONDITIONS AT LOWER & UPPER BOUND. 00000500 C IL,IU=2 1ST DERIVATIVE (VL,VU) AT LOWER OR UPPER BOUND RESP. 00000600 C IL,IU=3 2ND DERIVATIVE (VL,VU) AT LOWER OR UPPER BOUND RESP. 00000700 DIMENSION X(1), Y(1), E(1),U(1) 00000800 IF(IN.EQ.2) GO TO 40 00000900 N1=N-1 00001000 B1=X(2)-X(1) 00001100 C1=(Y(2)-Y(1))/B1 00001200 GO TO (12,14,16),IL 00001300 12 E(1)=1.0 00001400 U(1)=0.0 00001500 GO TO 18 00001600 14 E(1)=-.5 00001700 U(1)=(C1-VL)/2./B1 00001800 GO TO 18 00001900 16 E(1)=0. 00002000 U(1)=VL/12. 00002100 18 DO 20 J=2,N1 00002200 B2=X(J+1)-X(J) 00002300 C2=(Y(J+1)-Y(J))/B2 00002400 B=X(J+1)-X(J-1) 00002500 D=(C2-C1)/B 00002600 C=B1/B 00002700 B1=B2 00002800 C1=C2 00002900 P=C*E(J-1)+2.0 00003000 E(J)=(C-1.0)/P 00003100 20 U(J)=(D-C*U(J-1))/P 00003200 IF(IU.EQ.2) GO TO 24 00003300 IF(IU.EQ.1) E(N)=U(N1)/(1.0-E(N1)) 00003400 IF(IU.EQ.3) E(N)=VU/12.0 00003500 GO TO 26 00003600 24 C2=VU-(Y(N)-Y(N1))/(X(N)-X(N1)) 00003700 E(N)=(C2/(X(N)-X(N1))-U(N1))/(2.0E0+E(N1)) 00003800 26 DO 30 KK=1,N1 00003900 K=N-KK 00004000 E(K)=E(K)*E(K+1)+U(K) 00004100 IF(IN.EQ.0) GO TO 30 00004200 C ARRAY U CONTAINS THE DERIVATIVES OF THE SPLINE FUNCTION AT THE 00004300 C KNOTS 00004400 B2=X(K+1)-X(K) 00004500 U(K)=(Y(K+1)-Y(K))/B2-B2*(E(K)*2+E(K+1)) 00004600 30 CONTINUE 00004700 IF(IN.EQ.0) GO TO 40 00004800 B2=X(N)-X(N1) 00004900 U(N)=(E(N1)+2.0D0*E(N))*B2+(Y(N)-Y(N1))/B2 00005000 40 IF (X(1).GT.X(N)) GO TO 50 00005100 IDIR=0 00005200 MLB=0 00005300 MUB=N 00005400 GO TO 60 00005500 50 IDIR=1 00005600 MLB=N 00005700 MUB=0 00005800 60 IF (S.GE.X(MUB+IDIR)) GO TO 100 00005900 IF (S.LE.X(MLB+1-IDIR)) GO TO 110 00006000 ML=MLB 00006100 MU=MUB 00006200 GO TO 80 00006300 70 IF (IABS(MU-ML).LE.1) GO TO 120 00006400 80 MAV=(ML+MU)/2 00006500 IF(S.LT.X(MAV)) MU=MAV 00006600 IF(S.GE.X(MAV)) ML=MAV 00006700 GO TO 70 00006800 100 MU=MUB+2*IDIR 00006900 GO TO 130 00007000 110 MU=MLB+2*(1-IDIR) 00007100 GO TO 130 00007200 120 MU=MU+IDIR 00007300 130 T=(E(MU-1)*((X(MU)-S)**3)+E(MU)*((S-X(MU-1))**3)+ 00007400 1 (Y(MU-1)-E(MU-1)*((X(MU)-X(MU-1))**2))*(X(MU)-S)+ 00007500 2 (Y(MU)-E(MU)*((X(MU)-X(MU-1))**2))*(S-X(MU-1)))/(X(MU)-X(MU-1)) 00007600 RETURN 00007700 END 00007800