?spev
?spev
Computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix in packed storage.
Syntax
lapack_int
LAPACKE_sspev
(
int
matrix_layout
,
char
jobz
,
char
uplo
,
lapack_int
n
,
float
*
ap
,
float
*
w
,
float
*
z
,
lapack_int
ldz
);
lapack_int
LAPACKE_dspev
(
int
matrix_layout
,
char
jobz
,
char
uplo
,
lapack_int
n
,
double
*
ap
,
double
*
w
,
double
*
z
,
lapack_int
ldz
);
Include Files
- mkl.h
Description
The routine computes all the eigenvalues and, optionally, eigenvectors of a real symmetric matrix
A
in packed storage.Input Parameters
- matrix_layout
- Specifies whether matrix storage layout is row major (LAPACK_ROW_MAJOR) or column major (LAPACK_COL_MAJOR).
- jobz
- Must be'N'or'V'.If, then only eigenvalues are computed.job='N'If, then eigenvalues and eigenvectors are computed.job='V'
- uplo
- Must be'U'or'L'.If,uplo='U'apstores the packed upper triangular part ofA.If,uplo='L'apstores the packed lower triangular part ofA.
- n
- The order of the matrixA().n≥0
- ap
- Arrayapcontains the packed upper or lower triangle of symmetric matrixA, as specified byuplo.The size ofapmust be at least max(1,n*(n+1)/2).
- ldz
- The leading dimension of the output arrayz. Constraints:if, thenjobz='N';ldz≥1if, thenjobz='V'.ldz≥max(1,n)
Output Parameters
- w,z
- Arrays:w, size at least max(1,n).If,info= 0wcontains the eigenvalues of the matrixAin ascending order.z(size max(1,.ldz*n))If, then ifjobz='V',info= 0zcontains the orthonormal eigenvectors of the matrixA, with thei-th column ofzholding the eigenvector associated with.w[i- 1]If, thenjobz='N'zis not referenced.
- ap
- On exit, this array is overwritten by the values generated during the reduction to tridiagonal form. The elements of the diagonal and the off-diagonal of the tridiagonal matrix overwrite the corresponding elements ofA.
Return Values
This function returns a value
info
.If , the execution is successful.
info
=0If , the
info
= -i
i
-th parameter had an illegal value.If , then the algorithm failed to converge;
info
= i
i
indicates the number of elements of an intermediate tridiagonal form which did not converge to zero.