# spotf2.f - Man Page

SRC/spotf2.f

## Synopsis

### Functions/Subroutines

subroutine **spotf2** (uplo, n, a, lda, info)**SPOTF2** computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

## Function/Subroutine Documentation

### subroutine spotf2 (character uplo, integer n, real, dimension( lda, * ) a, integer lda, integer info)

**SPOTF2** computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

**Purpose:**

SPOTF2 computes the Cholesky factorization of a real symmetric positive definite matrix A. The factorization has the form A = U**T * U , if UPLO = 'U', or A = L * L**T, 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.

**Parameters***UPLO*UPLO is CHARACTER*1 Specifies whether the upper or lower triangular part of the symmetric matrix A is stored. = 'U': Upper triangular = 'L': Lower triangular

*N*N is INTEGER The order of the matrix A. N >= 0.

*A*A is REAL 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**T *U or A = L*L**T.

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

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

**Author**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **108** of file **spotf2.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page spotf2(3) is an alias of spotf2.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK