LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

Go to the source code of this file.
Functions/Subroutines  
subroutine  slasq3 (I0, N0, Z, PP, DMIN, SIGMA, DESIG, QMAX, NFAIL, ITER, NDIV, IEEE, TTYPE, DMIN1, DMIN2, DN, DN1, DN2, G, TAU) 
SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr. 
subroutine slasq3  (  integer  I0, 
integer  N0,  
real, dimension( * )  Z,  
integer  PP,  
real  DMIN,  
real  SIGMA,  
real  DESIG,  
real  QMAX,  
integer  NFAIL,  
integer  ITER,  
integer  NDIV,  
logical  IEEE,  
integer  TTYPE,  
real  DMIN1,  
real  DMIN2,  
real  DN,  
real  DN1,  
real  DN2,  
real  G,  
real  TAU  
) 
SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.
Download SLASQ3 + dependencies [TGZ] [ZIP] [TXT]SLASQ3 checks for deflation, computes a shift (TAU) and calls dqds. In case of failure it changes shifts, and tries again until output is positive.
[in]  I0  I0 is INTEGER First index. 
[in,out]  N0  N0 is INTEGER Last index. 
[in]  Z  Z is REAL array, dimension ( 4*N ) Z holds the qd array. 
[in,out]  PP  PP is INTEGER PP=0 for ping, PP=1 for pong. PP=2 indicates that flipping was applied to the Z array and that the initial tests for deflation should not be performed. 
[out]  DMIN  DMIN is REAL Minimum value of d. 
[out]  SIGMA  SIGMA is REAL Sum of shifts used in current segment. 
[in,out]  DESIG  DESIG is REAL Lower order part of SIGMA 
[in]  QMAX  QMAX is REAL Maximum value of q. 
[out]  NFAIL  NFAIL is INTEGER Number of times shift was too big. 
[out]  ITER  ITER is INTEGER Number of iterations. 
[out]  NDIV  NDIV is INTEGER Number of divisions. 
[in]  IEEE  IEEE is LOGICAL Flag for IEEE or non IEEE arithmetic (passed to SLASQ5). 
[in,out]  TTYPE  TTYPE is INTEGER Shift type. 
[in,out]  DMIN1  DMIN1 is REAL 
[in,out]  DMIN2  DMIN2 is REAL 
[in,out]  DN  DN is REAL 
[in,out]  DN1  DN1 is REAL 
[in,out]  DN2  DN2 is REAL 
[in,out]  G  G is REAL 
[in,out]  TAU  TAU is REAL These are passed as arguments in order to save their values between calls to SLASQ3. 
Definition at line 181 of file slasq3.f.