---
name: "dla_porpvgrw"
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/dla_porpvgrw.f"
---

# dla\_porpvgrw(3)

Part of [dla\_porpvgrw.f(3)](/dla_porpvgrw.f/3.md).

## NAME

SRC/dla\_porpvgrw.f

## SYNOPSIS

### Functions/Subroutines

double precision function **dla\_porpvgrw** (uplo, ncols, a, lda, af, ldaf, work)\
 **DLA\_PORPVGRW** computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric or Hermitian positive-definite matrix.

## Function/Subroutine Documentation

### double precision function dla\_porpvgrw (character\*1 uplo, integer ncols, double precision, dimension( lda, \* ) a, integer lda, double precision, dimension( ldaf, \* ) af, integer ldaf, double precision, dimension( \* ) work)

**DLA\_PORPVGRW** computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric or Hermitian positive-definite matrix.

**Purpose:**

```
!>
!>
!> DLA_PORPVGRW computes the reciprocal pivot growth factor
!> norm(A)/norm(U). The  norm is used. If this is
!> much less than 1, the stability of the LU factorization of the
!> (equilibrated) matrix A could be poor. This also means that the
!> solution X, estimated condition numbers, and error bounds could be
!> unreliable.
!>
```

**Parameters**

*UPLO*

```
!>          UPLO is CHARACTER*1
!>       = 'U':  Upper triangle of A is stored;
!>       = 'L':  Lower triangle of A is stored.
!>
```

*NCOLS*

```
!>          NCOLS is INTEGER
!>     The number of columns of the matrix A. NCOLS >= 0.
!>
```

*A*

```
!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>     On entry, the N-by-N matrix A.
!>
```

*LDA*

```
!>          LDA is INTEGER
!>     The leading dimension of the array A.  LDA >= max(1,N).
!>
```

*AF*

```
!>          AF is DOUBLE PRECISION array, dimension (LDAF,N)
!>     The triangular factor U or L from the Cholesky factorization
!>     A = U**T*U or A = L*L**T, as computed by DPOTRF.
!>
```

*LDAF*

```
!>          LDAF is INTEGER
!>     The leading dimension of the array AF.  LDAF >= max(1,N).
!>
```

*WORK*

```
!>          WORK is DOUBLE PRECISION array, dimension (2*N)
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **104** of file **dla\_porpvgrw.f**.

## Author

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