SRC/ssygst.f(3)

💖 SRC/ssygst.f(3) 💖

Library Functions Manual, bestie — welcome to the Unix-manual group chat. 🫶✨

🌸 NAME 🌸

SRC/ssygst.f — the page for the ssygst subroutine, and it's giving “reduce a real symmetric-definite generalized eigenproblem to standard form.” 💅

🦋 SYNOPSIS 🦋

Functions/Subroutines

• subroutine ssygst (itype, uplo, n, a, lda, b, ldb, info) — SSYGST.

🧚 Function/Subroutine Documentation 🧚

subroutine ssygst (integer itype, character uplo, integer n, real,
       dimension( lda, * ) a, integer lda, real, dimension( ldb, * ) b, integer
       ldb, integer info)

This one is SSYGST, no cap. 👑

💖 Purpose 💖

SSYGST reduces a real symmetric-definite generalized eigenproblem to standard form. ✨

If ITYPE = 1, the problem is A*x = lambda*B*x, and A is overwritten by inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T).

If ITYPE = 2 or 3, the problem is A*B*x = lambda*x or B*A*x = lambda*x, and A is overwritten by U*A*U**T or L**T*A*L.

B must have been previously factorized as U**T*U or L*L**T by SPOTRF. 🫶

🎀 Parameters 🎀

ITYPE

ITYPE is INTEGER.

• = 1: compute inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T);
• = 2 or 3: compute U*A*U**T or L**T*A*L.

UPLO

UPLO is CHARACTER*1.

• = 'U': Upper triangle of A is stored and B is factored as U**T*U;
• = 'L': Lower triangle of A is stored and B is factored as L*L**T.

N

N is INTEGER. The order of the matrices A and B. N >= 0.

A

A is REAL array, dimension (LDA,N).

On entry, the symmetric matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced.

On exit, if INFO = 0, the transformed matrix, stored in the same format as A. 💫

LDA

LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,N).

B

B is REAL array, dimension (LDB,N). The triangular factor from the Cholesky factorization of B, as returned by SPOTRF.

LDB

LDB is INTEGER. The leading dimension of the array B. LDB >= max(1,N).

INFO

INFO is INTEGER.

• = 0: successful exit
• < 0: if INFO = -i, the i-th argument had an illegal value

👑 Author 👑

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 126 of file ssygst.f.

🌟 Author 🌟

Generated automatically by Doxygen for LAPACK from the source code.

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Bye bestie — LAPACK Version 3.12.0, SRC/ssygst.f(3), and that's the footer sign-off. 💅🎀🦋