-
template<typename T>
void tftri(char *transr, char *uplo, char *diag, integer *n, T *a, integer *info)# TFTRI computes the inverse of a triangular matrix A stored in RFP format.
Purpose:
TFTRI computes the inverse of a triangular matrix A stored in RFP format. This is a Level 3 BLAS version of the algorithm.
- Parameters:
TRANSR – [in]
TRANSR is CHARACTER*1
= ‘N’: The Normal TRANSR of RFP A is stored;
= ‘T’: The Transpose TRANSR of RFP A is stored.UPLO – [in]
UPLO is CHARACTER*1
= ‘U’: A is upper triangular;
= ‘L’: A is lower triangular.DIAG – [in]
DIAG is CHARACTER*1
= ‘N’: A is non-unit triangular;
= ‘U’: A is unit triangular.N – [in]
N is INTEGER
The order of the matrix A. N >= 0.
A – [inout]
A is REAL array, dimension (NT);
NT=N*(N+1)/2. On entry, the triangular factor of a Hermitian Positive Definite matrix A in RFP format. RFP format is described by TRANSR, UPLO, and N as follows: If TRANSR = ‘N’ then RFP A is (0:N,0:k-1) when N is even; k=N/2. RFP A is (0:N-1,0:k) when N is odd; k=N/2. IF TRANSR = ‘T’ then RFP is the transpose of RFP A as defined when TRANSR = ‘N’. The contents of RFP A are defined by UPLO as follows: If UPLO = ‘U’ the RFP A contains the nt elements of upper packed A; If UPLO = ‘L’ the RFP A contains the nt elements of lower packed A. The LDA of RFP A is (N+1)/2 when TRANSR = ‘T’. When TRANSR is ‘N’ the LDA is N+1 when N is even and N is odd. See the Note below for more details.
On exit, the (triangular) inverse of the original matrix, in the same storage format.INFO – [out]
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, A(i,i) is exactly zero. The triangular matrix is singular and its inverse can not be computed.