LAUU2 - 5.2 English - 68552

AOCL API Guide (68552)

Document ID
68552
Release Date
2025-12-29
Version
5.2 English
template<typename T>
void lauu2(char *uplo, integer *n, T *a, integer *lda, integer *info)#

Product UUH or LHL, where U and L are upper or lower triangular matrices (unblocked algorithm).

Purpose:

    Product UUH or LHL, where U and L are upper or lower triangular matrices (unblocked
algorithm). Computation of the product U * U**T or L**T * L, where the triangular factor U or L
is stored in the upper or lower triangular part of the array a.

    If uplo = 'U' or 'u' then the upper triangle of the result is stored, overwriting the factor
U in A. If uplo = 'L' or 'l' then the lower triangle of the result is stored, overwriting the
factor L in A.

    This is the unblocked form of the algorithm, calling Level 2 BLAS.
Parameters:
  • uplo[in]

    uplo is char*

    Specifies whether the triangular factor stored in the array a is upper or lower triangular:

    = ‘U’: Upper triangular

    = ‘L’: Lower triangular

  • n[in]

    n is integer*

    The order of the triangular factor U or L. n >= 0.

  • a[inout]

    a is float/double/COMPLEX/COMPLEX*16 array, dimension (lda,n)

    On entry, the triangular factor U or L.

    On exit, if uplo = ‘U’, the Upper triangle of a is overwritten with the upper triangle of the product U * U**T;

    if uplo = ‘L’, the lower triangle of a is overwritten with the lower triangle of the product L**T * L.

  • lda[in]

    lda is integer*

    The leading dimension of the matrix a, lda >= fla_max(1,n)

  • INFO[out]

    INFO is INTEGER

    = 0: successful exit

    < 0: if INFO = -k, the k-th argument had an illegal value