TESTING/LIN/slattp.f(3)

💅 TESTING/LIN/slattp.f(3) — Library Functions Manual ✨

okay so bestie, this is a page out of the LAPACK manual — literally the TESTING/LIN/slattp.f page, from the Library Functions Manual. no cap, it's a whole subroutine doc and we're gonna walk through it together 🫶

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🌸 NAME 🌸

TESTING/LIN/slattp.f — that's the file, that's the vibe. periodt.

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✨ SYNOPSIS ✨

Functions/Subroutines

• subroutine slattp (imat, uplo, trans, diag, iseed, n, a, b, work, info) — the one and only SLATTP 👑

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👑 Function/Subroutine Documentation 👑

subroutine slattp (integer imat, character uplo, character trans, character diag, integer, dimension( 4 ) iseed, integer n, real, dimension( * ) a, real, dimension( * ) b, real, dimension( * ) work, integer info)

SLATTP — she's the main character of this page, no notes 💅

🎀 Purpose 🎀

!> !> SLATTP generates a triangular test matrix in packed storage. !> IMAT and UPLO uniquely specify the properties of the test !> matrix, which is returned in the array AP. !>

so basically: IMAT + UPLO together decide exactly what kind of test matrix you're getting, and it comes back to you in the array AP. iconic behaviour honestly 🦋

🌈 Parameters 🌈

• IMAT — IMAT is INTEGER. It's the integer key describing which matrix to generate for this path. think of it as the "which fit am I wearing today" selector 🔥
• UPLO — UPLO is CHARACTER*1. Specifies whether the matrix A will be upper or lower triangular.
  • = 'U': Upper triangular
  • = 'L': Lower triangular
• TRANS — TRANS is CHARACTER*1. Specifies whether the matrix or its transpose will be used.
  • = 'N': No transpose
  • = 'T': Transpose
  • = 'C': Conjugate transpose (= Transpose)
• DIAG — DIAG is CHARACTER*1. Specifies whether or not the matrix A is unit triangular.
  • = 'N': Non-unit triangular
  • = 'U': Unit triangular
• ISEED — ISEED is INTEGER array, dimension (4). The seed vector for the random number generator (used in SLATMS). Modified on exit ⚠️ — yeah she changes on her way out, that's just how she is 🙈
• N — N is INTEGER. The order of the matrix to be generated. the size, the moment, the scale 💫
• A — A is REAL array, dimension (N*(N+1)/2). The upper or lower triangular 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((j-1)*j/2 + i) = A(i,j) for 1<=i<=j;
if UPLO = 'L',
   AP((j-1)*(n-j) + j*(j+1)/2 + i-j) = A(i,j) for j<=i<=n.

like, that indexing math is giving "I took AP Calc and I'm thriving" 😭 but it's literally just where each entry lives, iykyk 🧚

• B — B is REAL array, dimension (N). The right hand side vector, if IMAT > 10. note the condition bestie, don't forget it 💀
• WORK — WORK is REAL array, dimension (3*N). scratch space, the backstage area, we love her 🌸
• INFO — INFO is INTEGER.
  • = 0: successful exit ✨
  • < 0: if INFO = -k, the k-th argument had an illegal value 🚩

💖 Author 💖

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

Definition at line 123 of file slattp.f. 📍

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⭐ Author ⭐

Generated automatically by Doxygen for LAPACK from the source code. (so nobody hand-wrote this beauty, the robots did it 🤖💅)

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and that's the whole page, bestie — every flag, every formula, every author, all accounted for. slay 🎀

— with love, LAPACK Version 3.12.0, dated TESTING/LIN/slattp.f(3) 💜