ZTBCON(3)

🌸 NAME 🌸

Okay so bestie, this is ZTBCON(3) from the Library Functions Manual, and the header path — it shows up on both sides of the manual name — is /home/abui...RC/ztbcon.f(3). 💅

The NAME section is literally pointing at this source file:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/ztbcon.f

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✨ SYNOPSIS ✨

🌟 Functions/Subroutines 🌟

subroutine ZTBCON (norm, uplo, diag, n, kd, ab, ldab, rcond, work, rwork, info)
ZTBCON

💅 Function/Subroutine Documentation 💅

subroutine ZTBCON (character norm, character uplo, character diag, integer n, integer kd, complex*16, dimension( ldab, * ) ab, integer ldab, double precision rcond, complex*16, dimension( * ) work, double precision, dimension( * ) rwork, integer info)
ZTBCON

🎀 Purpose: 🎀

ZTBCON estimates the reciprocal of the condition number of a triangular band matrix A, in either the 1-norm or the infinity-norm.

It computes the norm of A and gets an estimate for norm(inv(A)), then the reciprocal of the condition number is computed as:

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

🧚 Parameters 🧚

• NORM — it's CHARACTER*1, and it specifies whether you need the 1-norm condition number or the infinity-norm condition number:

= '1' or 'O':  1-norm;
= 'I':         Infinity-norm.

• UPLO — CHARACTER*1:

= 'U':  A is upper triangular;
= 'L':  A is lower triangular.

• DIAG — CHARACTER*1:

= 'N':  A is non-unit triangular;
= 'U':  A is unit triangular.

• N — INTEGER, aka the order of the matrix A. Constraint: N >= 0.
• KD — INTEGER, the number of superdiagonals or subdiagonals of the triangular band matrix A. Constraint: KD >= 0.
• AB — COMPLEX*16 array, dimension (LDAB,N). It's the upper or lower triangular band matrix A, stored in the first kd+1 rows of the array. The j-th column of A is stored in the j-th column of the array AB as follows:

if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j;
if UPLO = 'L', AB(1+i-j,j)    = A(i,j) for j<=i<=min(n,j+kd).

If DIAG = 'U', the diagonal elements of A are not referenced and are assumed to be 1.

• LDAB — INTEGER, the leading dimension of the array AB. Constraint: LDAB >= KD+1.
• RCOND — DOUBLE PRECISION, the reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
• WORK — COMPLEX*16 array, dimension (2*N).
• RWORK — DOUBLE PRECISION array, dimension (N).
• INFO — INTEGER:

= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value

👑 Author 👑

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

Definition at line 141 of file ztbcon.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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Okay that's the whole page, bestie! 💖 Cute sign-off: source/version is LAPACK Version 3.12.0, and this footer doesn't give a date — just the path /home/abui...RC/ztbcon.f(3). ✨