SRC/cptsv.f(3)

💅 SRC/cptsv.f(3) — Library Functions Manual 💅

okay bestie, welcome to the SRC/cptsv.f page, part of the Library Functions Manual. this one's a Fortran gem and honestly? she's iconic. let's get into it 🫶

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✨ NAME ✨

SRC/cptsv.f

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🌸 SYNOPSIS 🌸

Functions/Subroutines

• subroutine cptsv (n, nrhs, d, e, b, ldb, info) — CPTSV computes the solution to system of linear equations A * X = B for PT matrices ✨

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🦋 Function/Subroutine Documentation 🦋

subroutine cptsv (integer n, integer nrhs, real, dimension( * ) d, complex,
    dimension( * ) e, complex, dimension( ldb, * ) b, integer ldb, integer
    info)

CPTSV computes the solution to system of linear equations A * X = B for PT matrices. 💖

🎀 Purpose 🎀

CPTSV computes the solution to a complex system of linear equations A*X = B, where A is an N-by-N Hermitian positive definite tridiagonal matrix, and X and B are N-by-NRHS matrices. A is factored as A = L*D*L**H, and the factored form of A is then used to solve the system of equations.

so basically she takes your fancy Hermitian positive definite tridiagonal matrix, factors it all cute-like, and then solves the whole system for you. main character energy fr fr 👑

🌈 Parameters 🌈

• N

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

it's giving "how big is your matrix", bestie. the order of A, and N >= 0 — no negative vibes allowed 🙈

• NRHS

NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.

how many right hand sides you're serving — like, the number of columns of the matrix B. NRHS >= 0, periodt.

• D

D is REAL array, dimension (N) On entry, the n diagonal elements of the tridiagonal matrix A. On exit, the n diagonal elements of the diagonal matrix D from the factorization A = L*D*L**H.

a REAL array, dimension (N). on entry it's holding the n diagonal elements of the tridiagonal matrix A; on exit it's the n diagonal elements of the diagonal matrix D from the factorization A = L*D*L**H. she literally transforms 💅

• E

E is COMPLEX array, dimension (N-1) On entry, the (n-1) subdiagonal elements of the tridiagonal matrix A. On exit, the (n-1) subdiagonal elements of the unit bidiagonal factor L from the L*D*LH factorization of A. E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the UH*D*U factorization of A.

a COMPLEX array, dimension (N-1). on entry: the (n-1) subdiagonal elements of the tridiagonal matrix A. on exit: the (n-1) subdiagonal elements of the unit bidiagonal factor L from the L*D*LH factorization of A. lowkey she's flexible too — E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the UH*D*U factorization of A 🦋

• B

B is COMPLEX array, dimension (LDB,NRHS) On entry, the N-by-NRHS right hand side matrix B. On exit, if INFO = 0, the N-by-NRHS solution matrix X.

COMPLEX array, dimension (LDB,NRHS). on entry it's the N-by-NRHS right hand side matrix B; on exit, if INFO = 0, it's the N-by-NRHS solution matrix X. glow-up of the century ✨

• LDB

LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N).

INTEGER, the leading dimension of the array B. LDB >= max(1,N) — don't test her, she will notice 😭

• INFO

INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, the leading principal minor of order i is not positive, and the solution has not been computed. The factorization has not been completed unless i = N.

INTEGER, the vibe check report:

• = 0: successful exit 🎉
• < 0: if INFO = -i, the i-th argument had an illegal value — rude 😤
• > 0: if INFO = i, the leading principal minor of order i is not positive, and the solution has not been computed. the factorization has not been completed unless i = N. so like, no solution for u bestie 💀

🧚 Author 🧚

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

⭐ Definition at line 114 of file cptsv.f. ⭐

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💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

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and that's the whole page, bestie 🍓 LAPACK Version 3.12.0, SRC/cptsv.f(3) — lovingly auto-generated by Doxygen for LAPACK straight from the source code. iykyk 💅💖