/home/abui...RC/sspev.f(3)

💅 NAME

This page is from the Library Functions Manual, and the title/file it's serving is /home/abui...RC/sspev.f(3).

The NAME line points at this source file: /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/sspev.f

✨ SYNOPSIS ✨

💫 Functions/Subroutines 💫

subroutine SSPEV (jobz, uplo, n, ap, w, z, ldz, work, info)

SSPEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrices.

🦋 Function/Subroutine Documentation 🦋

subroutine SSPEV (character jobz, character uplo, integer n, real, dimension( * ) ap, real, dimension( * ) w, real, dimension( ldz, * ) z, integer ldz, real, dimension( * ) work, integer info)

SSPEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrices.

🧚 Purpose 🧚

SSPEV computes all the eigenvalues and, optionally, eigenvectors of a real symmetric matrix A in packed storage. Periodt.

🎀 Parameters 🎀

🍓 JOBZ

• JOBZ is CHARACTER*1
  • = 'N': Compute eigenvalues only;
  • = 'V': Compute eigenvalues and eigenvectors.

🍓 UPLO

• UPLO is CHARACTER*1
  • = 'U': Upper triangle of A is stored;
  • = 'L': Lower triangle of A is stored.

🍓 N

• N is INTEGER
• The order of the matrix A. N >= 0.

🍓 AP

• AP is REAL array, dimension (N*(N+1)/2)
• On entry, the upper or lower triangle of the symmetric matrix A, packed 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.
• On exit, AP is overwritten by values generated during the reduction to tridiagonal form. If UPLO = 'U', the diagonal and first superdiagonal of the tridiagonal matrix T overwrite the corresponding elements of A, and if UPLO = 'L', the diagonal and first subdiagonal of T overwrite the corresponding elements of A.

🍓 W

• W is REAL array, dimension (N)
• If INFO = 0, the eigenvalues in ascending order.

🍓 Z

• Z is REAL array, dimension (LDZ, N)
• If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal eigenvectors of the matrix A, with the i-th column of Z holding the eigenvector associated with W(i).
• If JOBZ = 'N', then Z is not referenced.

🍓 LDZ

• LDZ is INTEGER
• The leading dimension of the array Z. LDZ >= 1, and if JOBZ = 'V', LDZ >= max(1,N).

🍓 WORK

• WORK is REAL array, dimension (3*N)

🍓 INFO

• INFO is INTEGER
  • = 0: successful exit.
  • < 0: if INFO = -i, the i-th argument had an illegal value.
  • > 0: if INFO = i, the algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero.

🫶 Author

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

Definition at line 129 of file sspev.f.

🫶 Author (the generated one)

Generated automatically by Doxygen for LAPACK from the source code.

---

Cute sign-off: LAPACK Version 3.12.0, /home/abui...RC/sspev.f(3) — that's the footer, bestie. 💖