C
C***********************************************************************
C
      SUBROUTINE SLAGER(N, NBAND, NSTART, A, TMIN, TMAX)
C
C  THIS SUBROUTINE COMPUTES BOUNDS ON THE SPECTRUM OF A BY
C  EXAMINING THE GERSCHGORIN CIRCLES. ONLY THE NEWLY CREATED
C  CIRCLES ARE EXAMINED
C
C  FORMAL PARAMETERS
C
      INTEGER N, NBAND, NSTART
      REAL A(NBAND,1), TMIN, TMAX
C
C  LOCAL VARIABLES
C
      INTEGER I, K, L, M
      REAL TEMP
C
C  FUNCTIONS CALLED
C
      INTEGER MIN0
      REAL AMIN1, AMAX1
C
      DO 50 K = NSTART, N
         TEMP = 0.0 
         DO 10 I = 2, NBAND
            TEMP = TEMP + ABS(A(I,K))
   10    CONTINUE
   20    L = MIN0(K,NBAND)
         IF(L .EQ. 1) GO TO 40
         DO 30 I = 2, L
            M = K - I + 1
            TEMP = TEMP + ABS(A(I,M))
   30    CONTINUE
   40    TMIN = AMIN1(TMIN, A(1,K)-TEMP)
         TMAX = AMAX1(TMAX, A(1,K)+TEMP)
   50 CONTINUE
      RETURN
      END

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