dlasq4.f (3) - Linux Manuals
NAME
dlasq4.f -
SYNOPSIS
Functions/Subroutines
subroutine dlasq4 (I0, N0, Z, PP, N0IN, DMIN, DMIN1, DMIN2, DN, DN1, DN2, TAU, TTYPE, G)
DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.
Function/Subroutine Documentation
subroutine dlasq4 (integerI0, integerN0, double precision, dimension( * )Z, integerPP, integerN0IN, double precisionDMIN, double precisionDMIN1, double precisionDMIN2, double precisionDN, double precisionDN1, double precisionDN2, double precisionTAU, integerTTYPE, double precisionG)
DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.
Purpose:
-
DLASQ4 computes an approximation TAU to the smallest eigenvalue using values of d from the previous transform.
Parameters:
-
I0
I0 is INTEGER First index.
N0N0 is INTEGER Last index.
ZZ is DOUBLE PRECISION array, dimension ( 4*N ) Z holds the qd array.
PPPP is INTEGER PP=0 for ping, PP=1 for pong.
N0INN0IN is INTEGER The value of N0 at start of EIGTEST.
DMINDMIN is DOUBLE PRECISION Minimum value of d.
DMIN1DMIN1 is DOUBLE PRECISION Minimum value of d, excluding D( N0 ).
DMIN2DMIN2 is DOUBLE PRECISION Minimum value of d, excluding D( N0 ) and D( N0-1 ).
DNDN is DOUBLE PRECISION d(N)
DN1DN1 is DOUBLE PRECISION d(N-1)
DN2DN2 is DOUBLE PRECISION d(N-2)
TAUTAU is DOUBLE PRECISION This is the shift.
TTYPETTYPE is INTEGER Shift type.
GG is REAL G is passed as an argument in order to save its value between calls to DLASQ4.
Author:
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Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
- September 2012
Further Details:
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CNST1 = 9/16
Definition at line 151 of file dlasq4.f.
Author
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