CLATSY(3)

🎀 CLATSY(3) 🎀

ok so this is a page from the Library Functions Manual, and bestie, we are diving into LAPACK testing-matrix territory. Buckle up. 💅

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✨ NAME ✨

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/clatsy.f

like, yes, the NAME section is literally just a file path. iconic of it honestly. 🫶

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✨ SYNOPSIS ✨

🌸 Functions/Subroutines

• subroutine CLATSY (uplo, n, x, ldx, iseed) — CLATSY

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✨ Function/Subroutine Documentation ✨

subroutine CLATSY (character uplo, integer n, complex, dimension( ldx, * )
    x, integer ldx, integer, dimension( * ) iseed)

CLATSY 💖

🦋 Purpose:

!>
!> CLATSY generates a special test matrix for the complex symmetric
!> (indefinite) factorization.  The pivot blocks of the generated matrix
!> will be in the following order:
!>    2x2 pivot block, non diagonalizable
!>    1x1 pivot block
!>    2x2 pivot block, diagonalizable
!>    (cycle repeats)
!> A row interchange is required for each non-diagonalizable 2x2 block.
!>

so basically it's generating a test matrix specifically for the complex symmetric (indefinite) factorization, and the pivot blocks come out in that exact order, cycling forever and ever. and heads up: a row interchange is required for each non-diagonalizable 2x2 block — that's not a vibe suggestion, that's a requirement. 🔥

🌈 Parameters

• UPLO

!>          UPLO is CHARACTER
!>          Specifies whether the generated matrix is to be upper or
!>          lower triangular.
!>          = 'U':  Upper triangular
!>          = 'L':  Lower triangular
!>

bestie it's giving "pick a triangle": 'U' for upper triangular, 'L' for lower triangular. choose wisely ✨

• N

!>          N is INTEGER
!>          The dimension of the matrix to be generated.
!>

the dimension of the matrix we're generating. no notes. 💜

• X

!>          X is COMPLEX array, dimension (LDX,N)
!>          The generated matrix, consisting of 3x3 and 2x2 diagonal
!>          blocks which result in the pivot sequence given above.
!>          The matrix outside of these diagonal blocks is zero.
!>

the actual generated matrix, and the way it's built is so specific: 3x3 and 2x2 diagonal blocks that produce that pivot sequence from up above. and everything outside those diagonal blocks? zero. clean. minimalist. main character energy honestly. 👑

• LDX

!>          LDX is INTEGER
!>          The leading dimension of the array X.
!>

leading dimension of X. that's it, that's the whole flag. 🎀

• ISEED

!>          ISEED is INTEGER array, dimension (4)
!>          On entry, the seed for the random number generator.  The last
!>          of the four integers must be odd.  (modified on exit)
!>

the seed for the random number generator — four integers, and the last one must be odd, fr fr, don't skip that. also note: it gets modified on exit. so don't come crying when your seed looks different afterwards, it literally told you. 💀

💫 Author

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

⭐ Definition at line 88 of file clatsy.f.

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🌸 Author

Generated automatically by Doxygen for LAPACK from the source code. (not a human, just doxygen doing its little autogen thing 🧚)

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and that's the whole page, bestie! ✨ LAPACK, Version 3.12.0, and this little number lives at /home/abui...IN/clatsy.f(3) — kudos to doxygen for the auto-generation, mwah 💋🫶