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2.4.5
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slabad.f
Go to the documentation of this file.
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SUBROUTINE
slabad
( SMALL, LARGE )
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*
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* -- LAPACK auxiliary routine (version 3.2) --
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* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
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* November 2006
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*
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* .. Scalar Arguments ..
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REAL
large, small
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* ..
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*
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* Purpose
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* =======
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*
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* SLABAD takes as input the values computed by SLAMCH for underflow and
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* overflow, and returns the square root of each of these values if the
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* log of LARGE is sufficiently large. This subroutine is intended to
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* identify machines with a large exponent range, such as the Crays, and
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* redefine the underflow and overflow limits to be the square roots of
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* the values computed by SLAMCH. This subroutine is needed because
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* SLAMCH does not compensate for poor arithmetic in the upper half of
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* the exponent range, as is found on a Cray.
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*
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* Arguments
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* =========
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*
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* SMALL (input/output) REAL
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* On entry, the underflow threshold as computed by SLAMCH.
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* On exit, if LOG10(LARGE) is sufficiently large, the square
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* root of SMALL, otherwise unchanged.
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*
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* LARGE (input/output) REAL
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* On entry, the overflow threshold as computed by SLAMCH.
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* On exit, if LOG10(LARGE) is sufficiently large, the square
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* root of LARGE, otherwise unchanged.
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*
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* =====================================================================
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*
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* .. Intrinsic Functions ..
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INTRINSIC
log10, sqrt
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* ..
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* .. Executable Statements ..
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*
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* If it looks like we're on a Cray, take the square root of
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* SMALL and LARGE to avoid overflow and underflow problems.
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*
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IF
( log10( large ).GT.2000. )
THEN
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small = sqrt( small )
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large = sqrt( large )
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END IF
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*
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return
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*
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* End of SLABAD
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*
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END
plasma_2.4.5
testing
lin
slabad.f
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