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C
C***********************************************************************
C
SUBROUTINE DLAGER(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
DOUBLE PRECISION A(NBAND,1), TMIN, TMAX
C
C LOCAL VARIABLES
C
INTEGER I, K, L, M
DOUBLE PRECISION TEMP
C
C FUNCTIONS CALLED
C
INTEGER MIN0
DOUBLE PRECISION DMIN1, DMAX1
C
DO 50 K = NSTART, N
TEMP = 0.0D0
DO 10 I = 2, NBAND
TEMP = TEMP + DABS(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 + DABS(A(I,M))
30 CONTINUE
40 TMIN = DMIN1(TMIN, A(1,K)-TEMP)
TMAX = DMAX1(TMAX, A(1,K)+TEMP)
50 CONTINUE
RETURN
END
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