DTPTTR(3)

🎀 DTPTTR(3) 🎀

ok so bestie, grab a strawberry 🍓 — we're diving into the LAPACK life. This page lives at /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dtpttr.f and honestly? it's giving "tiny file, huge destiny." 💅

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✨ SYNOPSIS ✨

🌸 Functions/Subroutines 🌸

• subroutine DTPTTR (uplo, n, ap, a, lda, info) — the whole point of this page: DTPTTR copies a triangular matrix from the standard packed format (TP) to the standard full format (TR). no cap, that's literally the entire job description.

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💖 Function/Subroutine Documentation 💖

subroutine DTPTTR (character uplo, integer n, double precision, dimension( * ) ap, double precision, dimension( lda, * ) a, integer lda, integer info)

DTPTTR copies a triangular matrix from the standard packed format (TP) to the standard full format (TR). that's it, that's the mission. 🫶

🦋 Purpose 🦋

!>
!> DTPTTR copies a triangular matrix A from standard packed format (TP)
!> to standard full format (TR).
!>

yes ma'am — packed in, full out. glow-up complete. ✨

👑 Parameters 👑

• UPLO

!>          UPLO is CHARACTER*1
!>          = 'U':  A is upper triangular.
!>          = 'L':  A is lower triangular.
!>

character, one (1) single char. 'U' means upper triangular, 'L' means lower triangular. pick your fighter. 💀

• N

!>          N is INTEGER
!>          The order of the matrix A. N >= 0.
!>

an integer, the order of matrix A, and it has to be N >= 0. no negativity allowed in this house. 🚫

• AP

!>          AP is DOUBLE PRECISION array, dimension ( N*(N+1)/2 ),
!>          On entry, 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(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.
!>

a DOUBLE PRECISION array of dimension ( N*(N+1)/2 ) — the input, bestie. on entry it's the upper or lower triangular matrix A, packed columnwise into a linear array. the j-th column of A gets stored like this:

• if UPLO = 'U', then AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
• if UPLO = 'L', then AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.

it's giving "index math is my love language." 🔥

• A

!>          A is DOUBLE PRECISION array, dimension ( LDA, N )
!>          On exit, the triangular 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.
!>

a DOUBLE PRECISION array, dimension ( LDA, N ). on exit this is the triangular matrix — the output, the main character. 🌟

• if UPLO = 'U': the leading N-by-N upper triangular part of A holds the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced (don't touch it, don't look at it 🙈);
• if UPLO = 'L': the leading N-by-N lower triangular part of A holds the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced (same energy, flipped 💅).

• LDA

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

integer, the leading dimension of the array A, and it must satisfy LDA >= max(1,N). rules are rules, bestie. 👑

• INFO

!>          INFO is INTEGER
!>          = 0:  successful exit
!>          < 0:  if INFO = -i, the i-th argument had an illegal value
!>

integer, the vibe check at the end:

• = 0: successful exit 🎉 slay!
• < 0: if INFO = -i, the i-th argument had an illegal value 😭 somebody passed a bad arg.

🧚 Author 🧚

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

(the academic avengers, fr fr 🫶)

⭐ Definition ⭐

Definition at line 103 of file dtpttr.f.

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. (so don't come for me about typos, a robot wrote the original 😌)

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ok that's the whole page bestie — every flag, every formula, nothing skipped. go forth and pack your triangles. 💜

LAPACK · Version 3.12.0 · /home/abui...RC/dtpttr.f(3) — mwah, that's the sign-off, ily, bye! 🎀💖🦋