---
name: "slapll"
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/slapll.f"
---

# slapll(3)

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

## NAME

SRC/slapll.f

## SYNOPSIS

### Functions/Subroutines

subroutine **slapll** (n, x, incx, y, incy, ssmin)\
 **SLAPLL** measures the linear dependence of two vectors.

## Function/Subroutine Documentation

### subroutine slapll (integer n, real, dimension( \* ) x, integer incx, real, dimension( \* ) y, integer incy, real ssmin)

**SLAPLL** measures the linear dependence of two vectors.

**Purpose:**

```
!>
!> Given two column vectors X and Y, let
!>
!>                      A = ( X Y ).
!>
!> The subroutine first computes the QR factorization of A = Q*R,
!> and then computes the SVD of the 2-by-2 upper triangular matrix R.
!> The smaller singular value of R is returned in SSMIN, which is used
!> as the measurement of the linear dependency of the vectors X and Y.
!>
```

**Parameters**

*N*

```
!>          N is INTEGER
!>          The length of the vectors X and Y.
!>
```

*X*

```
!>          X is REAL array,
!>                         dimension (1+(N-1)*INCX)
!>          On entry, X contains the N-vector X.
!>          On exit, X is overwritten.
!>
```

*INCX*

```
!>          INCX is INTEGER
!>          The increment between successive elements of X. INCX > 0.
!>
```

*Y*

```
!>          Y is REAL array,
!>                         dimension (1+(N-1)*INCY)
!>          On entry, Y contains the N-vector Y.
!>          On exit, Y is overwritten.
!>
```

*INCY*

```
!>          INCY is INTEGER
!>          The increment between successive elements of Y. INCY > 0.
!>
```

*SSMIN*

```
!>          SSMIN is REAL
!>          The smallest singular value of the N-by-2 matrix A = ( X Y ).
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **101** of file **slapll.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.