FUNCTION TERP (X,Y,XI,N,XMIN,IFLGSP)
C     ****
C     ****     PERFORMS LINEAR INTERPOLATION IN TABLE OF N (X,Y) POINTS
C     ****     X(N) IS ARRAY OF MONOTONICALLY INCREASING ABSCISSAE
C     ****     Y(N) IS ARRAY OF CORRESPONDING ORDINATES
C     ****     XI IS ABSCISSA AT WHICH INTERPOLATION IS REQUIRED
C     ****     N IS NUMBER OF POINTS IN TABLE
C     ****     INTERPOLATED VALUE IS RETURNED IN TERP
C     ****
C     ****
      DIMENSION X(1),Y(1)
C     ****
C     ****     SEARCH FOR INTERVAL IN WHICH XI FALLS
C     ****
C  XMIN =        The minimum spacing in X that XI is required to be
C                within bounds
C  IFLGSP = 0,1  Is flag indicating whether or not there is a large gap
C                (greater than XMIN) near the time XI
C
      IFLGSP = 0
      IF(N.EQ.1)THEN
           TERP=Y(1)
      ELSE
           NN=1
           DO 1 I=1,N-1
           IF(XI.GT.X(I))NN=I
    1      CONTINUE
C          ****
C          ****     PERFORM LINEAR INTERPOLATION
C          ****
           TERP=((X(NN+1)-XI)*Y(NN)+(XI-X(NN))*Y(NN+1))/(X(NN+1)-X(NN))
      IF (XI .LT. X(1)) TERP = Y(1)
      IF (XI .GT. X(N)) TERP = Y(N)
      DELTNP = ABS(X(NN+1)-XI)
      DELTNN = ABS(XI-X(NN))
      IF (DELTNP .GT. XMIN .AND. DELTNN .GT. XMIN) IFLGSP = 1
      ENDIF
      RETURN
      END