---
name: "dpotf2"
section: "3lapack"
platform: "linux"
package: "liblapack-doc"
version: "3.2.1-8"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/dpotf2/3lapack"
---

# dpotf2(3lapack)

computes the Cholesky factorization of a real symmetric positive definite matrix A

## NAME

DPOTF2 - computes the Cholesky factorization of a real symmetric positive definite matrix A

## SYNOPSIS

- SUBROUTINE DPOTF2(

  UPLO, N, A, LDA, INFO )

- CHARACTER

  UPLO

- INTEGER

  INFO, LDA, N

- DOUBLE

  PRECISION A( LDA, \* )

## PURPOSE

DPOTF2 computes the Cholesky factorization of a real symmetric positive definite matrix A. The factorization has the form\
\
    A = U' \* U ,  if UPLO = 'U', or\
\
    A = L  \* L',  if UPLO = 'L',\
 where U is an upper triangular matrix and L is lower triangular. This is the unblocked version of the algorithm, calling Level 2 BLAS.

## ARGUMENTS

- UPLO (input) CHARACTER\*1

  Specifies whether the upper or lower triangular part of the symmetric matrix A is stored. = 'U':  Upper triangular\
   \= 'L':  Lower triangular

- N (input) INTEGER

  The order of the matrix A.  N \>= 0.

- A (input/output) DOUBLE PRECISION array, dimension (LDA,N)

  On entry, the symmetric matrix A.  If UPLO = 'U', the leading n by n upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced.  If UPLO = 'L', the leading n by n lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced. On exit, if INFO = 0, the factor U or L from the Cholesky factorization A = U'\*U  or A = L\*L'.

- LDA (input) INTEGER

  The leading dimension of the array A.  LDA \>= max(1,N).

- INFO (output) INTEGER

  \= 0: successful exit\
   \< 0: if INFO = -k, the k-th argument had an illegal value\
   \> 0: if INFO = k, the leading minor of order k is not positive definite, and the factorization could not be completed.