---
name: "slasq5"
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/slasq5.f"
---

# slasq5(3)

Part of [slasq5.f(3)](/slasq5.f/3.md).

## NAME

SRC/slasq5.f

## SYNOPSIS

### Functions/Subroutines

subroutine **slasq5** (i0, n0, z, pp, tau, sigma, dmin, dmin1, dmin2, dn, dnm1, dnm2, ieee, eps)\
  **SLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.**

## Function/Subroutine Documentation

### subroutine slasq5 (integer i0, integer n0, real, dimension( \* ) z, integer pp, real tau, real sigma, real dmin, real dmin1, real dmin2, real dn, real dnm1, real dnm2, logical ieee, real eps)

 **SLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.**

**Purpose:**

```
!>
!> SLASQ5 computes one dqds transform in ping-pong form, one
!> version for IEEE machines another for non IEEE machines.
!>
```

**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. EMIN is stored in Z(4*N0) to avoid
!>        an extra argument.
!>
```

*PP*

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

*TAU*

```
!>          TAU is REAL
!>        This is the shift.
!>
```

*SIGMA*

```
!>          SIGMA is REAL
!>        This is the accumulated shift up to this step.
!>
```

*DMIN*

```
!>          DMIN is REAL
!>        Minimum value of d.
!>
```

*DMIN1*

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

*DMIN2*

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

*DN*

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

*DNM1*

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

*DNM2*

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

*IEEE*

```
!>          IEEE is LOGICAL
!>        Flag for IEEE or non IEEE arithmetic.
!>
```

*EPS*

```
!>         EPS is REAL
!>        This is the value of epsilon used.
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **142** of file **slasq5.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.