---
name: "zpot01.f"
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/zpot01.f"
---

# zpot01.f(3)

## NAME

TESTING/LIN/zpot01.f

## SYNOPSIS

### Functions/Subroutines

subroutine **zpot01** (uplo, n, a, lda, afac, ldafac, rwork, resid)\
 **ZPOT01**

## Function/Subroutine Documentation

### subroutine zpot01 (character uplo, integer n, complex\*16, dimension( lda, \* ) a, integer lda, complex\*16, dimension( ldafac, \* ) afac, integer ldafac, double precision, dimension( \* ) rwork, double precision resid)

**ZPOT01**

**Purpose:**

```
!>
!> ZPOT01 reconstructs a Hermitian positive definite matrix  A  from
!> its L*L' or U'*U factorization and computes the residual
!>    norm( L*L' - A ) / ( N * norm(A) * EPS ) or
!>    norm( U'*U - A ) / ( N * norm(A) * EPS ),
!> where EPS is the machine epsilon, L' is the conjugate transpose of L,
!> and U' is the conjugate transpose of U.
!>
```

**Parameters**

*UPLO*

```
!>          UPLO is CHARACTER*1
!>          Specifies whether the upper or lower triangular part of the
!>          Hermitian matrix A is stored:
!>          = 'U':  Upper triangular
!>          = 'L':  Lower triangular
!>
```

*N*

```
!>          N is INTEGER
!>          The number of rows and columns of the matrix A.  N >= 0.
!>
```

*A*

```
!>          A is COMPLEX*16 array, dimension (LDA,N)
!>          The original Hermitian matrix A.
!>
```

*LDA*

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

*AFAC*

```
!>          AFAC is COMPLEX*16 array, dimension (LDAFAC,N)
!>          On entry, the factor L or U from the L * L**H or U**H * U
!>          factorization of A.
!>          Overwritten with the reconstructed matrix, and then with
!>          the difference L * L**H - A (or U**H * U - A).
!>
```

*LDAFAC*

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

*RWORK*

```
!>          RWORK is DOUBLE PRECISION array, dimension (N)
!>
```

*RESID*

```
!>          RESID is DOUBLE PRECISION
!>          If UPLO = 'L', norm(L * L**H - A) / ( N * norm(A) * EPS )
!>          If UPLO = 'U', norm(U**H * U - A) / ( N * norm(A) * EPS )
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **105** of file **zpot01.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.