potf2(3)

NAME
potf2 - potf2: triangular factor panel, level 2

SYNOPSIS

  Functions
subroutine cpotf2 (uplo, n, a, lda, info)
CPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).
subroutine dpotf2 (uplo, n, a, lda, info)
DPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).
subroutine spotf2 (uplo, n, a, lda, info)
SPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).
subroutine zpotf2 (uplo, n, a, lda, info)
ZPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

Detailed Description

Function Documentation

  subroutine cpotf2 (character uplo, integer n, complex, dimension( lda, * ) a, integer lda, integer info)

CPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

Purpose:

    !>
    !> CPOTF2 computes the Cholesky factorization of a complex Hermitian
    !> positive definite matrix A.
    !>
    !> The factorization has the form
    !>    A = U**H * U ,  if UPLO = 'U', or
    !>    A = L  * L**H,  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
    !>          Hermitian 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 COMPLEX array, dimension (LDA,N)
    !>          On entry, the Hermitian 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**H *U  or A = L*L**H.
    !>

    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 cpotf2.f.

  subroutine dpotf2 (character uplo, integer n, double precision, dimension( lda, * ) a, integer lda, integer info)

DPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

Purpose:

    !>
    !> DPOTF2 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 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**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 dpotf2.f.

  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.

  subroutine zpotf2 (character uplo, integer n, complex*16, dimension( lda, * ) a, integer lda, integer info)

ZPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

Purpose:

    !>
    !> ZPOTF2 computes the Cholesky factorization of a complex Hermitian
    !> positive definite matrix A.
    !>
    !> The factorization has the form
    !>    A = U**H * U ,  if UPLO = 'U', or
    !>    A = L  * L**H,  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
    !>          Hermitian 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 COMPLEX*16 array, dimension (LDA,N)
    !>          On entry, the Hermitian 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**H *U  or A = L*L**H.
    !>

    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 zpotf2.f.

Author

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