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Diffstat (limited to 'eigen/lapack/dlapy3.f')
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diff --git a/eigen/lapack/dlapy3.f b/eigen/lapack/dlapy3.f new file mode 100644 index 0000000..ae9844f --- /dev/null +++ b/eigen/lapack/dlapy3.f @@ -0,0 +1,111 @@ +*> \brief \b DLAPY3 +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +*> \htmlonly +*> Download DLAPY3 + dependencies +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlapy3.f"> +*> [TGZ]</a> +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlapy3.f"> +*> [ZIP]</a> +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlapy3.f"> +*> [TXT]</a> +*> \endhtmlonly +* +* Definition: +* =========== +* +* DOUBLE PRECISION FUNCTION DLAPY3( X, Y, Z ) +* +* .. Scalar Arguments .. +* DOUBLE PRECISION X, Y, Z +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> +*> DLAPY3 returns sqrt(x**2+y**2+z**2), taking care not to cause +*> unnecessary overflow. +*> \endverbatim +* +* Arguments: +* ========== +* +*> \param[in] X +*> \verbatim +*> X is DOUBLE PRECISION +*> \endverbatim +*> +*> \param[in] Y +*> \verbatim +*> Y is DOUBLE PRECISION +*> \endverbatim +*> +*> \param[in] Z +*> \verbatim +*> Z is DOUBLE PRECISION +*> X, Y and Z specify the values x, y and z. +*> \endverbatim +* +* Authors: +* ======== +* +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. +* +*> \date November 2011 +* +*> \ingroup auxOTHERauxiliary +* +* ===================================================================== + DOUBLE PRECISION FUNCTION DLAPY3( X, Y, Z ) +* +* -- LAPACK auxiliary routine (version 3.4.0) -- +* -- LAPACK is a software package provided by Univ. of Tennessee, -- +* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- +* November 2011 +* +* .. Scalar Arguments .. + DOUBLE PRECISION X, Y, Z +* .. +* +* ===================================================================== +* +* .. Parameters .. + DOUBLE PRECISION ZERO + PARAMETER ( ZERO = 0.0D0 ) +* .. +* .. Local Scalars .. + DOUBLE PRECISION W, XABS, YABS, ZABS +* .. +* .. Intrinsic Functions .. + INTRINSIC ABS, MAX, SQRT +* .. +* .. Executable Statements .. +* + XABS = ABS( X ) + YABS = ABS( Y ) + ZABS = ABS( Z ) + W = MAX( XABS, YABS, ZABS ) + IF( W.EQ.ZERO ) THEN +* W can be zero for max(0,nan,0) +* adding all three entries together will make sure +* NaN will not disappear. + DLAPY3 = XABS + YABS + ZABS + ELSE + DLAPY3 = W*SQRT( ( XABS / W )**2+( YABS / W )**2+ + $ ( ZABS / W )**2 ) + END IF + RETURN +* +* End of DLAPY3 +* + END |