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template<typename T>
void tptri(char *uplo, char *diag, integer *n, T *ap, integer *info)# TPTRI computes the inverse of a real upper or lower triangular
matrix A.
Purpose:
TPTRI computes the inverse of a real upper or lower triangular matrix A stored in packed format.
- Parameters:
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.
AP – [inout]
AP is REAL array, dimension (N*(N+1)/2)
On entry, the upper or lower triangular matrix A, stored columnwise in a linear array. The j-th column of A is stored in the array AP as follows:
if UPLO = ‘U’, AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = ‘L’, AP(i + (j-1)*((2*n-j)/2) = A(i,j) for j<=i<=n.
See below for further details. On exit, the (triangular) inverse of the original matrix, in the same packed 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.