Visible to Intel only — GUID: GUID-0B05C432-282C-4F97-8C2F-1146D5309A24
Visible to Intel only — GUID: GUID-0B05C432-282C-4F97-8C2F-1146D5309A24
?potf2
Computes the Cholesky factorization of a symmetric/Hermitian positive-definite matrix (unblocked algorithm).
Syntax
call spotf2( uplo, n, a, lda, info )
call dpotf2( uplo, n, a, lda, info )
call cpotf2( uplo, n, a, lda, info )
call zpotf2( uplo, n, a, lda, info )
Include Files
- mkl.fi
Description
The routine ?potf2 computes the Cholesky factorization of a real symmetric or complex Hermitian positive definite matrix A. The factorization has the form
A = UT*U for real flavors, A = UH*U for complex flavors if uplo = 'U', or
A = L*LT for real flavors, A = L*LH for complex flavors if uplo = 'L',
where U is an upper triangular matrix, and L is lower triangular.
This is the unblocked version of the algorithm, calling BLAS Level 2 Routines
Input Parameters
- uplo
-
CHARACTER*1.
Specifies whether the upper or lower triangular part of the symmetric/Hermitian matrix A is stored.
= 'U': upper triangular
= 'L': lower triangular
- n
-
INTEGER. The order of the matrix A. n≥ 0.
- a
-
REAL for spotf2
DOUBLE PRECISION or dpotf2
COMPLEX for cpotf2
DOUBLE COMPLEX for zpotf2.
Array, DIMENSION (lda, n).
On entry, the symmetric/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.
- lda
-
INTEGER. The leading dimension of the array a.
lda≥ max(1,n).
Output Parameters
- a
-
On exit, If info = 0, the factor U or L from the Cholesky factorization A=UT*U (A=UH*U), or A= L*LT (A = L*LH).
- info
-
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.