2. EL 7
  3. lapack
  4. SLASQ3(3)

Scroll to navigation

slasq3.f(3) LAPACK slasq3.f(3)

NAME

slasq3.f -

SYNOPSIS

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.

Function/Subroutine Documentation

subroutine slasq3 (integerI0, integerN0, real, dimension( * )Z, integerPP, realDMIN, realSIGMA, realDESIG, realQMAX, integerNFAIL, integerITER, integerNDIV, logicalIEEE, integerTTYPE, realDMIN1, realDMIN2, realDN, realDN1, realDN2, realG, realTAU)

SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

Purpose: 



 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.

Parameters:

I0 



          I0 is INTEGER


         First index.

N0



          N0 is INTEGER


         Last index.

Z



          Z is REAL array, dimension ( 4*N )


         Z holds the qd array.

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.

DMIN



          DMIN is REAL


         Minimum value of d.

SIGMA



          SIGMA is REAL


         Sum of shifts used in current segment.

DESIG



          DESIG is REAL


         Lower order part of SIGMA

QMAX



          QMAX is REAL


         Maximum value of q.

NFAIL



          NFAIL is INTEGER


         Number of times shift was too big.

ITER



          ITER is INTEGER


         Number of iterations.

NDIV



          NDIV is INTEGER


         Number of divisions.

IEEE



          IEEE is LOGICAL


         Flag for IEEE or non IEEE arithmetic (passed to SLASQ5).

TTYPE



          TTYPE is INTEGER


         Shift type.

DMIN1



          DMIN1 is REAL

DMIN2



          DMIN2 is REAL

DN



          DN is REAL

DN1



          DN1 is REAL

DN2



          DN2 is REAL

G



          G is REAL

TAU



          TAU is REAL


         These are passed as arguments in order to save their values


         between calls to SLASQ3.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 181 of file slasq3.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Tue Sep 25 2012 Version 3.4.2