SRC/ztpcon.f(3)

🎀 SRC/ztpcon.f 🎀

This page is SRC/ztpcon.f(3), and it's living in the Library Functions Manual. 💖

✨ NAME ✨

SRC/ztpcon.f

🦋 SYNOPSIS 🦋

Functions/Subroutines

• subroutine ztpcon (norm, uplo, diag, n, ap, rcond, work, rwork, info) — ZTPCON

💅 Function/Subroutine Documentation 💅

subroutine ztpcon (character norm, character uplo, character diag, integer n, complex*16, dimension( * ) ap, double precision rcond, complex*16, dimension( * ) work, double precision, dimension( * ) rwork, integer info)

ZTPCON

Ok so this is ZTPCON, the icon. 👑

🎯 Purpose

ZTPCON estimates the reciprocal of the condition number of a packed triangular matrix A, in either the 1-norm or the infinity-norm. No cap.

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

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

🧸 Parameters

• NORM — NORM is CHARACTER*1. Specifies whether the 1-norm condition number or the infinity-norm condition number is required:
  • = '1' or 'O': 1-norm;
  • = 'I': Infinity-norm.
• UPLO — UPLO is CHARACTER*1
  • = 'U': A is upper triangular;
  • = 'L': A is lower triangular.
• DIAG — DIAG is CHARACTER*1
  • = 'N': A is non-unit triangular;
  • = 'U': A is unit triangular.
• N — N is INTEGER. The order of the matrix A. N >= 0.
• AP — AP is COMPLEX*16 array, dimension (N*(N+1)/2). The upper or lower triangular matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows:

if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.

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

• RCOND — RCOND is DOUBLE PRECISION. The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
• WORK — WORK is COMPLEX*16 array, dimension (2*N)
• RWORK — RWORK is DOUBLE PRECISION array, dimension (N)
• INFO — INFO is 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 128 of file ztpcon.f.

🌈 Author 🌈

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