---
name: "dlasq6"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/dlasq6.f"
---

# dlasq6(3)

Part of [dlasq6.f(3)](/dlasq6.f/3.md).

## NAME

SRC/dlasq6.f

## SYNOPSIS

### Functions/Subroutines

subroutine **dlasq6** (i0, n0, z, pp, dmin, dmin1, dmin2, dn, dnm1, dnm2)\
 **DLASQ6** computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

## Function/Subroutine Documentation

### subroutine dlasq6 (integer i0, integer n0, double precision, dimension( \* ) z, integer pp, double precision dmin, double precision dmin1, double precision dmin2, double precision dn, double precision dnm1, double precision dnm2)

**DLASQ6** computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

**Purpose:**

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

**Parameters**

*I0*

```
!>          I0 is INTEGER
!>        First index.
!>
```

*N0*

```
!>          N0 is INTEGER
!>        Last index.
!>
```

*Z*

```
!>          Z is DOUBLE PRECISION array, dimension ( 4*N )
!>        Z holds the qd array. EMIN is stored in Z(4*N0) to avoid
!>        an extra argument.
!>
```

*PP*

```
!>          PP is INTEGER
!>        PP=0 for ping, PP=1 for pong.
!>
```

*DMIN*

```
!>          DMIN is DOUBLE PRECISION
!>        Minimum value of d.
!>
```

*DMIN1*

```
!>          DMIN1 is DOUBLE PRECISION
!>        Minimum value of d, excluding D( N0 ).
!>
```

*DMIN2*

```
!>          DMIN2 is DOUBLE PRECISION
!>        Minimum value of d, excluding D( N0 ) and D( N0-1 ).
!>
```

*DN*

```
!>          DN is DOUBLE PRECISION
!>        d(N0), the last value of d.
!>
```

*DNM1*

```
!>          DNM1 is DOUBLE PRECISION
!>        d(N0-1).
!>
```

*DNM2*

```
!>          DNM2 is DOUBLE PRECISION
!>        d(N0-2).
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **117** of file **dlasq6.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.