Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?lasq3
Checks for deflation, computes a shift and calls dqds . Used by ?bdsqr .
Syntax
call slasq3 ( i0 , n0 , z , pp , dmin , sigma , desig , qmax , nfail , iter , ndiv , ieee , ttype , dmin1 , dmin2 , dn , dn1 , dn2 , g , tau )
call dlasq3 ( i0 , n0 , z , pp , dmin , sigma , desig , qmax , nfail , iter , ndiv , ieee , ttype , dmin1 , dmin2 , dn , dn1 , dn2 , g , tau )
Include Files
mkl.fi
Description
slasq3 dlasq3
The routine ?lasq3 checks for deflation, computes a shift tau , and calls dqds . In case of failure, it changes shifts, and tries again until output is positive.
Input Parameters
- i0
-
INTEGER . First index.
- n0
-
INTEGER . Last index.
- z
-
REAL for slasq3 DOUBLE PRECISION for dlasq3 . Array, DIMENSION (4 n ). z holds the qd array.
- pp
-
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.
- desig
-
REAL for slasq3 DOUBLE PRECISION for dlasq3 . Lower order part of sigma .
- qmax
-
REAL for slasq3 DOUBLE PRECISION for dlasq3 . Maximum value of q .
- ieee
-
LOGICAL . Flag for ieee or non- ieee arithmetic (passed to ?lasq5 ).
- ttype
-
INTEGER . Shift type.
- dmin1 , dmin2 , dn , dn1 , dn2 , g , tau
-
REAL for slasq3 DOUBLE PRECISION for dlasq3 . These scalars are passed as arguments in order to save their values between calls to ?lasq3 .
Output Parameters
- dmin
-
REAL for slasq3 DOUBLE PRECISION for dlasq3 . Minimum value of d .
- pp
-
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.
- sigma
-
REAL for slasq3 DOUBLE PRECISION for dlasq3 . Sum of shifts used in the current segment.
- desig
-
Lower order part of sigma .
- nfail
-
INTEGER . Number of times shift was too big.
- iter
-
INTEGER . Number of iterations.
- ndiv
-
INTEGER . Number of divisions.
- ttype
-
INTEGER . Shift type.
- dmin1 , dmin2 , dn , dn1 , dn2 , g , tau
-
REAL for slasq3 DOUBLE PRECISION for dlasq3 . These scalars are passed as arguments in order to save their values between calls to ?lasq3 .