SRC/dgecon.f(3)

💅 SRC/dgecon.f(3) 💅

okay so this is the Library Functions Manual page for SRC/dgecon.f(3), and the main character is DGECON. bestie, it’s giving linear algebra with full group-chat energy. 💖✨

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💖 NAME 💖

SRC/dgecon.f — that’s the name, periodt. This whole page is the DGECON documentation, no cap.

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

subroutine dgecon (norm, n, a, lda, anorm, rcond, work, iwork, info)

That’s the short tea: DGECON.

🎀 Function/Subroutine Documentation 🎀

subroutine dgecon (character norm, integer n, double precision, dimension(
     lda, * ) a, integer lda, double precision anorm, double precision rcond,
     double precision, dimension( * ) work, integer, dimension( * ) iwork,
     integer info)

👑 DGECON 👑

✨ Purpose ✨

okay so DGECON estimates the reciprocal of the condition number of a general real matrix A, in either the 1-norm or the infinity-norm, using the LU factorization computed by DGETRF.

An estimate is obtained for norm(inv(A)), and then the reciprocal of the condition number is computed as:

RCOND = 1 / ( norm(A) * norm(inv(A)) )

obsessed with the math, honestly. 💅

🌸 Parameters 🌸

• NORM — is CHARACTER*1. It specifies whether the 1-norm condition number or the infinity-norm condition number is required:
  • = '1' or 'O': 1-norm;
  • = 'I': Infinity-norm.
• N — is INTEGER. The order of the matrix A. N >= 0.
• A — is DOUBLE PRECISION array, dimension (LDA,N). The factors L and U from the factorization A = P*L*U as computed by DGETRF.
• LDA — is INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• ANORM — is DOUBLE PRECISION. If NORM = '1' or 'O', the 1-norm of the original matrix A. If NORM = 'I', the infinity-norm of the original matrix A.
• RCOND — is DOUBLE PRECISION. The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
• WORK — is DOUBLE PRECISION array, dimension (4*N).
• IWORK — is INTEGER array, dimension (N).
• INFO — is INTEGER, and here’s the status tea:
  • = 0: successful exit.
  • < 0: if INFO = -i, the i-th argument had an illegal value. NaNs are illegal values for ANORM, and they propagate to the output parameter RCOND. Infinity is illegal for ANORM, and it propagates to the output parameter RCOND as 0.
  • = 1: if RCOND = NaN, or RCOND = Inf, or the computed norm of the inverse of A is 0. In the latter, RCOND = 0 is returned.

👑 Author 👑

the author squad is:

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

Definition at line 130 of file dgecon.f.

🤖 Author (auto-generated edition) 🤖

Generated automatically by Doxygen for LAPACK from the source code.

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🌸 footer tea: LAPACK Version 3.12.0, SRC/dgecon.f(3), and no date listed on this page — that’s the whole sign-off, bestie. bye! 💅✨