getrs(3)

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version 3.12.1 · 9 versions
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💅 getrs(3) — LAPACK's triangular solve bestie has entered the chat ✨

🌸 NAME 🌸

getrs — getrs: triangular solve using factor. That's the name, and it ate. 💅

🎀 SYNOPSIS 🎀

🧚 Functions

  • subroutine cgetrs (trans, n, nrhs, a, lda, ipiv, b, ldb, info) — CGETRS
  • subroutine dgetrs (trans, n, nrhs, a, lda, ipiv, b, ldb, info) — DGETRS
  • subroutine sgetrs (trans, n, nrhs, a, lda, ipiv, b, ldb, info) — SGETRS
  • subroutine zgetrs (trans, n, nrhs, a, lda, ipiv, b, ldb, info) — ZGETRS

💖 Detailed Description 💖

This section is short and sweet in the source — it rolls straight into Function Documentation. So consider this your lil' hallway pass, bestie: the real subroutine tea is right below. 🫶

🌈 Function Documentation 🌈

💫 cgetrs — CGETRS

   subroutine cgetrs (character trans, integer n, integer nrhs, complex,
       dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv,
       complex, dimension( ldb, * ) b, integer ldb, integer info)
       CGETRS

🎯 Purpose

CGETRS solves a system of linear equations

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

with a general N-by-N matrix A using the LU factorization computed by CGETRF. Iconic. ✨

🧮 Parameters

  • TRANS — CHARACTER*1. 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 — INTEGER. The order of the matrix A. N >= 0.
  • NRHS — INTEGER. The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
  • A — COMPLEX array, dimension (LDA,N). The factors L and U from the factorization A = P*L*U as computed by CGETRF.
  • LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N).
  • IPIV — INTEGER array, dimension (N). The pivot indices from CGETRF; for 1<=i<=N, row i of the matrix was interchanged with row IPIV(i).
  • B — COMPLEX array, dimension (LDB,NRHS). On entry, the right hand side matrix B. On exit, the solution matrix X.
  • LDB — INTEGER. The leading dimension of the array B. LDB >= max(1,N).
  • INFO — INTEGER.
    • = 0: successful exit
    • < 0: if INFO = -i, the i-th argument had an illegal value
Heads up: that INFO < 0 line means an argument was illegal — don't ignore it, bestie. 💀

🫶 Author

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

📍 Definition

Definition at line 120 of file cgetrs.f.

💫 dgetrs — DGETRS

   subroutine dgetrs (character trans, integer n, integer nrhs, double
       precision, dimension( lda, * ) a, integer lda, integer, dimension( * )
       ipiv, double precision, dimension( ldb, * ) b, integer ldb, integer
       info)
       DGETRS

🎯 Purpose

DGETRS solves a system of linear equations

A * X = B  or  A**T * X = B

with a general N-by-N matrix A using the LU factorization computed by DGETRF. Slay. 💅

🧮 Parameters

  • TRANS — CHARACTER*1. Specifies the form of the system of equations:
    • = 'N': A * X = B (No transpose)
    • = 'T': A**T* X = B (Transpose)
    • = 'C': A**T* X = B (Conjugate transpose = Transpose)
  • N — INTEGER. The order of the matrix A. N >= 0.
  • NRHS — INTEGER. The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
  • A — DOUBLE PRECISION array, dimension (LDA,N). The factors L and U from the factorization A = P*L*U as computed by DGETRF.
  • LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N).
  • IPIV — INTEGER array, dimension (N). The pivot indices from DGETRF; for 1<=i<=N, row i of the matrix was interchanged with row IPIV(i).
  • B — DOUBLE PRECISION array, dimension (LDB,NRHS). On entry, the right hand side matrix B. On exit, the solution matrix X.
  • LDB — INTEGER. The leading dimension of the array B. LDB >= max(1,N).
  • INFO — INTEGER.
    • = 0: successful exit
    • < 0: if INFO = -i, the i-th argument had an illegal value
Heads up: same energy as above — INFO < 0 is your “girl, check that argument” signal. 🙈

🫶 Author

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

📍 Definition

Definition at line 120 of file dgetrs.f.

💫 sgetrs — SGETRS

   subroutine sgetrs (character trans, integer n, integer nrhs, real,
       dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, real,
       dimension( ldb, * ) b, integer ldb, integer info)
       SGETRS

🎯 Purpose

SGETRS solves a system of linear equations

A * X = B  or  A**T * X = B

with a general N-by-N matrix A using the LU factorization computed by SGETRF. Obsessed. 🫶

🧮 Parameters

  • TRANS — CHARACTER*1. Specifies the form of the system of equations:
    • = 'N': A * X = B (No transpose)
    • = 'T': A**T* X = B (Transpose)
    • = 'C': A**T* X = B (Conjugate transpose = Transpose)
  • N — INTEGER. The order of the matrix A. N >= 0.
  • NRHS — INTEGER. The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
  • A — REAL array, dimension (LDA,N). The factors L and U from the factorization A = P*L*U as computed by SGETRF.
  • LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N).
  • IPIV — INTEGER array, dimension (N). The pivot indices from SGETRF; for 1<=i<=N, row i of the matrix was interchanged with row IPIV(i).
  • B — REAL array, dimension (LDB,NRHS). On entry, the right hand side matrix B. On exit, the solution matrix X.
  • LDB — INTEGER. The leading dimension of the array B. LDB >= max(1,N).
  • INFO — INTEGER.
    • = 0: successful exit
    • < 0: if INFO = -i, the i-th argument had an illegal value
Heads up: INFO < 0 is not a vibe — it literally means an argument had an illegal value. 😭

🫶 Author

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

📍 Definition

Definition at line 120 of file sgetrs.f.

💫 zgetrs — ZGETRS

   subroutine zgetrs (character trans, integer n, integer nrhs, complex*16,
       dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv,
       complex*16, dimension( ldb, * ) b, integer ldb, integer info)
       ZGETRS

🎯 Purpose

ZGETRS solves a system of linear equations

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

with a general N-by-N matrix A using the LU factorization computed by ZGETRF. Main character subroutine behavior. 👑✨

🧮 Parameters

  • TRANS — CHARACTER*1. 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 — INTEGER. The order of the matrix A. N >= 0.
  • NRHS — INTEGER. The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
  • A — COMPLEX*16 array, dimension (LDA,N). The factors L and U from the factorization A = P*L*U as computed by ZGETRF.
  • LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N).
  • IPIV — INTEGER array, dimension (N). The pivot indices from ZGETRF; for 1<=i<=N, row i of the matrix was interchanged with row IPIV(i).
  • B — COMPLEX*16 array, dimension (LDB,NRHS). On entry, the right hand side matrix B. On exit, the solution matrix X.
  • LDB — INTEGER. The leading dimension of the array B. LDB >= max(1,N).
  • INFO — INTEGER.
    • = 0: successful exit
    • < 0: if INFO = -i, the i-th argument had an illegal value
Heads up: INFO < 0 means an illegal argument — address it, bestie, no cap. 💀

🫶 Author

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

📍 Definition

Definition at line 120 of file zgetrs.f.

📜 Author

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