Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?lauu2
Computes the product U*U^{T} ( U*U^{H} ) or L^{T}*L ( L^{H}*L ), where U and L are upper or lower triangular matrices (unblocked algorithm).
Syntax
call slauu2(uplo, n, a, lda, info)
call dlauu2(uplo, n, a, lda, info)
call clauu2(uplo, n, a, lda, info)
call zlauu2(uplo, n, a, lda, info)
Include Files
mkl.fi
Description
The routine ?lauu2 computes the product U*U^{T} or L^{T}*L for real flavors, and U*U^{H} or L^{H}*L for complex flavors. Here 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 BLAS Level 2 Routines .
Input Parameters
- uplo
-
CHARACTER*1 . Specifies whether the triangular factor stored in the array a is upper or lower triangular: = ‘U’ : Upper triangular = ‘L’ : Lower triangular
- n
-
INTEGER . The order of the triangular factor U or L . n≥ 0 .
- a
-
REAL for slauu2 DOUBLE PRECISION for dlauu2 COMPLEX for clauu2 DOUBLE COMPLEX for zlauu2 . Array, DIMENSION ( lda , n ). On entry, the triangular factor U or L .
- lda
-
INTEGER . The leading dimension of the array a . lda≥ max(1,n) .
Output Parameters
- a
-
On exit, if uplo = 'U' , then the upper triangle of a is overwritten with the upper triangle of the product U*U^{T} ( U*U^{H} ); if uplo = 'L' , then the lower triangle of a is overwritten with the lower triangle of the product L^{T}*L ( L^{H}*L ).
info
INTEGER .
= 0: successful exit
< 0: if info = -k , the k -th argument had an illegal value