# slasq3.f - Man Page

SRC/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 (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.

**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*N0 ) 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 Increment NFAIL by 1 each time the shift was too big.

*ITER*ITER is INTEGER Increment ITER by 1 for each iteration.

*NDIV*NDIV is INTEGER Increment NDIV by 1 for each division.

*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.

Definition at line **179** of file **slasq3.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page slasq3(3) is an alias of slasq3.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK