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*
************************************************************************
*
SUBROUTINE DLAMC4( EMIN, START, BASE )
*
* -- LAPACK auxiliary routine (version 2.0) --
* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
* Courant Institute, Argonne National Lab, and Rice University
* October 31, 1992
*
* .. Scalar Arguments ..
INTEGER BASE, EMIN
DOUBLE PRECISION START
* ..
*
* Purpose
* =======
*
* DLAMC4 is a service routine for DLAMC2.
*
* Arguments
* =========
*
* EMIN (output) EMIN
* The minimum exponent before (gradual) underflow, computed by
* setting A = START and dividing by BASE until the previous A
* can not be recovered.
*
* START (input) DOUBLE PRECISION
* The starting point for determining EMIN.
*
* BASE (input) INTEGER
* The base of the machine.
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I
DOUBLE PRECISION A, B1, B2, C1, C2, D1, D2, ONE, RBASE, ZERO
* ..
* .. External Functions ..
DOUBLE PRECISION DLAMC3
EXTERNAL DLAMC3
* ..
* .. Executable Statements ..
*
A = START
ONE = 1
RBASE = ONE / BASE
ZERO = 0
EMIN = 1
B1 = DLAMC3( A*RBASE, ZERO )
C1 = A
C2 = A
D1 = A
D2 = A
*+ WHILE( ( C1.EQ.A ).AND.( C2.EQ.A ).AND.
* $ ( D1.EQ.A ).AND.( D2.EQ.A ) )LOOP
10 CONTINUE
IF( ( C1.EQ.A ) .AND. ( C2.EQ.A ) .AND. ( D1.EQ.A ) .AND.
$ ( D2.EQ.A ) ) THEN
EMIN = EMIN - 1
A = B1
B1 = DLAMC3( A / BASE, ZERO )
C1 = DLAMC3( B1*BASE, ZERO )
D1 = ZERO
DO 20 I = 1, BASE
D1 = D1 + B1
20 CONTINUE
B2 = DLAMC3( A*RBASE, ZERO )
C2 = DLAMC3( B2 / RBASE, ZERO )
D2 = ZERO
DO 30 I = 1, BASE
D2 = D2 + B2
30 CONTINUE
GO TO 10
END IF
*+ END WHILE
*
RETURN
*
* End of DLAMC4
*
END
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