SRC/claqsp.f(3)

🫶 SRC/claqsp.f(3) 🫶

Okay so we're in the Library Functions Manual, bestie, and this page is all about SRC/claqsp.f. It's giving very specific Fortran routine energy, and honestly? Iconic.

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🎀 NAME 🎀

SRC/claqsp.f — that's the name. Periodt.

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✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

• subroutine claqsp (uplo, n, ap, s, scond, amax, equed) — CLAQSP scales a symmetric/Hermitian matrix in packed storage, using scaling factors computed by sppequ.

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🔥 Function/Subroutine Documentation 🔥

subroutine claqsp (character uplo, integer n, complex, dimension( * ) ap, real, dimension( * ) s, real scond, real amax, character equed)

CLAQSP scales a symmetric/Hermitian matrix in packed storage, using scaling factors computed by sppequ. Yes, we're back with the same summary, because the manual said it twice and we respect the lore.

💡 Purpose 💡

So the whole point, bestie: CLAQSP equilibrates a symmetric matrix A using the scaling factors in the vector S. That's the purpose. That's the vibe. 💅

🌸 Parameters 🌸

• UPLO — UPLO is CHARACTER*1. It specifies whether the upper or lower triangular part of the symmetric matrix A is stored. = 'U': Upper triangular; = 'L': Lower triangular.
• N — N is INTEGER. The order of the matrix A. N >= 0.
• AP — AP is COMPLEX array, dimension (N*(N+1)/2). On entry, it's 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, you get the equilibrated matrix: diag(S) * A * diag(S), in the same storage format as A.
• S — S is REAL array, dimension (N). The scale factors for A.
• SCOND — SCOND is REAL. Ratio of the smallest S(i) to the largest S(i).
• AMAX — AMAX is REAL. Absolute value of largest matrix entry.
• EQUED — EQUED is CHARACTER*1. It specifies whether or not equilibration was done. = 'N': No equilibration.; = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).

🔒 Internal Parameters 🔒

• THRESH — a threshold value used to decide if scaling should be done based on the ratio of the scaling factors. If SCOND < THRESH, scaling is done.
• LARGE and SMALL — threshold values used to decide if scaling should be done based on the absolute size of the largest matrix element. If AMAX > LARGE or AMAX < SMALL, scaling is done.

👑 Author 👑

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

Definition at line 125 of file claqsp.f.

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👑 Author (Doxygen edition) 👑

Generated automatically by Doxygen for LAPACK from the source code.

💖 That's the whole page, bestie! Footer sign-off: LAPACK, Version 3.12.0, source SRC/claqsp.f(3) — no date in the footer, so we're not inventing one. Mwah! 💖