---
name: "dlasq6"
section: "3lapack"
platform: "linux"
package: "liblapack-doc"
version: "3.2.1-8"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/dlasq6/3lapack"
---

# dlasq6(3lapack)

computes one dqd (shift equal to zero) transform in ping-pong form, with protection against underflow and overflow

## NAME

DLASQ6 - computes one dqd (shift equal to zero) transform in ping-pong form, with protection against underflow and overflow

## SYNOPSIS

- SUBROUTINE DLASQ6(

  I0, N0, Z, PP, DMIN, DMIN1, DMIN2, DN, DNM1, DNM2 )

- INTEGER

  I0, N0, PP

- DOUBLE

  PRECISION DMIN, DMIN1, DMIN2, DN, DNM1, DNM2

- DOUBLE

  PRECISION Z( \* )

## PURPOSE

DLASQ6 computes one dqd (shift equal to zero) transform in ping-pong form, with protection against underflow and overflow.

## ARGUMENTS

- I0 (input) INTEGER

  First index.

- N0 (input) INTEGER

  Last index.

- Z (input) DOUBLE PRECISION array, dimension ( 4\*N )

  Z holds the qd array. EMIN is stored in Z(4\*N0) to avoid an extra argument.

- PP (input) INTEGER

  PP=0 for ping, PP=1 for pong.

- DMIN (output) DOUBLE PRECISION

  Minimum value of d. DMIN1 (output) DOUBLE PRECISION Minimum value of d, excluding D( N0 ). DMIN2 (output) DOUBLE PRECISION Minimum value of d, excluding D( N0 ) and D( N0-1 ).

- DN (output) DOUBLE PRECISION

  d(N0), the last value of d.

- DNM1 (output) DOUBLE PRECISION

  d(N0-1).

- DNM2 (output) DOUBLE PRECISION

  d(N0-2).