SRC/sspgst.f(3)

✨ SRC/sspgst.f ✨

okay so this is the Library Functions Manual page for SRC/sspgst.f, and bestie, it's giving Fortran subroutine realness with packed storage. no cap. 💅

🌸 NAME 🌸

SRC/sspgst.f

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

subroutine sspgst (itype, uplo, n, ap, bp, info)
           SSPGST

💅 Function/Subroutine Documentation 💅

subroutine sspgst (integer itype, character uplo, integer n, real,
       dimension( * ) ap, real, dimension( * ) bp, integer info)
       SSPGST

🌟 Purpose 🌟

SSPGST reduces a real symmetric-definite generalized eigenproblem to standard form, using packed storage. periodt. 💖

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 SPPTRF. fr fr, that part is required. 🫶

🦋 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. math bestie ✨
• 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)*(2n-j)/2) = A(i,j) for j<=i<=n.
  • On exit, if INFO = 0, the transformed matrix, stored in the
  • same format as A.
• BP — BP is REAL array, dimension (N*(N+1)/2)
  • The triangular factor from the Cholesky factorization of B,
  • stored in the same format as A, as returned by SPPTRF.
• 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 112 of file sspgst.f.

🫶 Author 🫶

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that's the whole page, bestie — LAPACK Version 3.12.0, SRC/sspgst.f(3), and yes the footer is serving iconic energy. 💖✨🎀