SRC/dgetri.f(3)

💅 NAME

SRC/dgetri.f — hii bestie, welcome to the Library Functions Manual page for SRC/dgetri.f(3). This is the DGETRI routine's corner of the LAPACK universe, and it's giving major main-character linear algebra energy 🫶

✨ SYNOPSIS ✨

Functions/Subroutines

   subroutine dgetri (n, a, lda, ipiv, work, lwork, info)
       DGETRI

🦋 Function/Subroutine Documentation

subroutine dgetri (integer n, double precision, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, double precision, dimension( * ) work, integer lwork, integer info)

   subroutine dgetri (integer n, double precision, dimension( lda, * ) a,
       integer lda, integer, dimension( * ) ipiv, double precision, dimension(
       * ) work, integer lwork, integer info)
       DGETRI

🌸 Purpose

Okay so DGETRI computes the inverse of a matrix using the LU factorization computed by DGETRF.

This method inverts U and then computes inv(A) by solving the system inv(A)*L = inv(U) for inv(A). Slay ✨

🎀 Parameters

• N — N is INTEGER. The order of the matrix A. Constraint: N >= 0.
• A — A is DOUBLE PRECISION array, dimension (LDA,N). On entry, the factors L and U from the factorization A = P*L*U as computed by DGETRF. On exit, if INFO = 0, the inverse of the original matrix A.
• LDA — LDA is INTEGER. The leading dimension of the array A. Constraint: LDA >= max(1,N).
• IPIV — IPIV is INTEGER array, dimension (N). The pivot indices from DGETRF; for 1<=i<=N, row i of the matrix was interchanged with row IPIV(i).
• WORK — WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)). On exit, if INFO=0, then WORK(1) returns the optimal LWORK.
• LWORK — LWORK is INTEGER. The dimension of the array WORK. Constraint: LWORK >= max(1,N). For optimal performance LWORK >= N*NB, where NB is the optimal blocksize returned by ILAENV.

If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.

• INFO — INFO is INTEGER:
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value
  • > 0: if INFO = i, U(i,i) is exactly zero; the matrix is singular and its inverse could not be computed.

🌈 Author

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

Definition at line 113 of file dgetri.f.

👑 Author

Generated automatically by Doxygen for LAPACK from the source code.

xoxo, your Unix bestie 🍓 — the footer signs off with LAPACK, version 3.12.0, under SRC/dgetri.f(3). Bye bestie 💖