diff options
author | jofret | 2009-04-28 07:17:00 +0000 |
---|---|---|
committer | jofret | 2009-04-28 07:17:00 +0000 |
commit | 8c8d2f518968ce7057eec6aa5cd5aec8faab861a (patch) | |
tree | 3dd1788b71d6a3ce2b73d2d475a3133580e17530 /src/lib/lapack/dlas2.f | |
parent | 9f652ffc16a310ac6641a9766c5b9e2671e0e9cb (diff) | |
download | scilab2c-8c8d2f518968ce7057eec6aa5cd5aec8faab861a.tar.gz scilab2c-8c8d2f518968ce7057eec6aa5cd5aec8faab861a.tar.bz2 scilab2c-8c8d2f518968ce7057eec6aa5cd5aec8faab861a.zip |
Moving lapack to right place
Diffstat (limited to 'src/lib/lapack/dlas2.f')
-rw-r--r-- | src/lib/lapack/dlas2.f | 121 |
1 files changed, 0 insertions, 121 deletions
diff --git a/src/lib/lapack/dlas2.f b/src/lib/lapack/dlas2.f deleted file mode 100644 index e100a4d8..00000000 --- a/src/lib/lapack/dlas2.f +++ /dev/null @@ -1,121 +0,0 @@ - SUBROUTINE DLAS2( F, G, H, SSMIN, SSMAX ) -* -* -- LAPACK auxiliary routine (version 3.1) -- -* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. -* November 2006 -* -* .. Scalar Arguments .. - DOUBLE PRECISION F, G, H, SSMAX, SSMIN -* .. -* -* Purpose -* ======= -* -* DLAS2 computes the singular values of the 2-by-2 matrix -* [ F G ] -* [ 0 H ]. -* On return, SSMIN is the smaller singular value and SSMAX is the -* larger singular value. -* -* Arguments -* ========= -* -* F (input) DOUBLE PRECISION -* The (1,1) element of the 2-by-2 matrix. -* -* G (input) DOUBLE PRECISION -* The (1,2) element of the 2-by-2 matrix. -* -* H (input) DOUBLE PRECISION -* The (2,2) element of the 2-by-2 matrix. -* -* SSMIN (output) DOUBLE PRECISION -* The smaller singular value. -* -* SSMAX (output) DOUBLE PRECISION -* The larger singular value. -* -* Further Details -* =============== -* -* Barring over/underflow, all output quantities are correct to within -* a few units in the last place (ulps), even in the absence of a guard -* digit in addition/subtraction. -* -* In IEEE arithmetic, the code works correctly if one matrix element is -* infinite. -* -* Overflow will not occur unless the largest singular value itself -* overflows, or is within a few ulps of overflow. (On machines with -* partial overflow, like the Cray, overflow may occur if the largest -* singular value is within a factor of 2 of overflow.) -* -* Underflow is harmless if underflow is gradual. Otherwise, results -* may correspond to a matrix modified by perturbations of size near -* the underflow threshold. -* -* ==================================================================== -* -* .. Parameters .. - DOUBLE PRECISION ZERO - PARAMETER ( ZERO = 0.0D0 ) - DOUBLE PRECISION ONE - PARAMETER ( ONE = 1.0D0 ) - DOUBLE PRECISION TWO - PARAMETER ( TWO = 2.0D0 ) -* .. -* .. Local Scalars .. - DOUBLE PRECISION AS, AT, AU, C, FA, FHMN, FHMX, GA, HA -* .. -* .. Intrinsic Functions .. - INTRINSIC ABS, MAX, MIN, SQRT -* .. -* .. Executable Statements .. -* - FA = ABS( F ) - GA = ABS( G ) - HA = ABS( H ) - FHMN = MIN( FA, HA ) - FHMX = MAX( FA, HA ) - IF( FHMN.EQ.ZERO ) THEN - SSMIN = ZERO - IF( FHMX.EQ.ZERO ) THEN - SSMAX = GA - ELSE - SSMAX = MAX( FHMX, GA )*SQRT( ONE+ - $ ( MIN( FHMX, GA ) / MAX( FHMX, GA ) )**2 ) - END IF - ELSE - IF( GA.LT.FHMX ) THEN - AS = ONE + FHMN / FHMX - AT = ( FHMX-FHMN ) / FHMX - AU = ( GA / FHMX )**2 - C = TWO / ( SQRT( AS*AS+AU )+SQRT( AT*AT+AU ) ) - SSMIN = FHMN*C - SSMAX = FHMX / C - ELSE - AU = FHMX / GA - IF( AU.EQ.ZERO ) THEN -* -* Avoid possible harmful underflow if exponent range -* asymmetric (true SSMIN may not underflow even if -* AU underflows) -* - SSMIN = ( FHMN*FHMX ) / GA - SSMAX = GA - ELSE - AS = ONE + FHMN / FHMX - AT = ( FHMX-FHMN ) / FHMX - C = ONE / ( SQRT( ONE+( AS*AU )**2 )+ - $ SQRT( ONE+( AT*AU )**2 ) ) - SSMIN = ( FHMN*C )*AU - SSMIN = SSMIN + SSMIN - SSMAX = GA / ( C+C ) - END IF - END IF - END IF - RETURN -* -* End of DLAS2 -* - END |