SRC/cgttrs.f(3)

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version 3.12.1 · 7 versions
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🎀 NAME 🎀

hey bestie 💖 welcome to the Library Functions Manual page for SRC/cgttrs.f — yes, the whole NAME section is literally just that: SRC/cgttrs.f. This is LAPACK business, and CGTTRS is the main character. 🫶

✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

subroutine cgttrs (trans, n, nrhs, dl, d, du, du2, ipiv, b, ldb, info)
    CGTTRS

💅 Function/Subroutine Documentation 💅

👑 subroutine cgttrs 👑

subroutine cgttrs (character trans, integer n, integer nrhs, complex,
    dimension( * ) dl, complex, dimension( * ) d, complex, dimension( * )
    du, complex, dimension( * ) du2, integer, dimension( * ) ipiv, complex,
    dimension( ldb, * ) b, integer ldb, integer info)
    CGTTRS

🌸 Purpose 🌸

okay so bestie, CGTTRS solves one of these systems of equations:

A * X = B,  A**T * X = B,  or  A**H * X = B,

with a tridiagonal matrix A using the LU factorization computed by CGTTRF. That’s the whole assignment, and it ate. 💅

🍓 Parameters 🍓

🌈 TRANS 🌈

TRANS is CHARACTER*1. It specifies the form of the system of equations.

  • = 'N': A * X = B (No transpose)
  • = 'T': A**T * X = B (Transpose)
  • = 'C': A**H * X = B (Conjugate transpose)

🌟 N 🌟

N is INTEGER. The order of the matrix A. 👑

🦋 NRHS 🦋

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

💜 DL 💜

DL is COMPLEX array, dimension (N-1). The (n-1) multipliers that define the matrix L from the LU factorization of A.

🎀 D 🎀

D is COMPLEX array, dimension (N). The n diagonal elements of the upper triangular matrix U from the LU factorization of A.

🧚 DU 🧚

DU is COMPLEX array, dimension (N-1). The (n-1) elements of the first super-diagonal of U.

🌸 DU2 🌸

DU2 is COMPLEX array, dimension (N-2). The (n-2) elements of the second super-diagonal of U.

🔥 IPIV 🔥

IPIV is INTEGER array, dimension (N). The pivot indices; for 1 <= i <= n, row i of the matrix was interchanged with row IPIV(i). IPIV(i) will always be either i or i+1; IPIV(i) = i indicates a row interchange was not required.

🍓 B 🍓

B is COMPLEX array, dimension (LDB,NRHS). On entry, the matrix of right hand side vectors B. On exit, B is overwritten by the solution vectors X.

🌈 LDB 🌈

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

💀 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 136 of file cgttrs.f.

🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code. ✨

later, bestie 🫶 this cutie is from LAPACK Version 3.12.0, page SRC/cgttrs.f(3). 💅✨

📦 where this page comes from