DTPT01(3)

💖 NAME 💖

Okay bestie, this is the Library Functions Manual page for /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/dtpt01.f — specifically the dtpt01.f(3) page for the actual DTPT01 routine. You're in the right place, no cap. 🫶

✨ SYNOPSIS ✨

Functions/Subroutines

subroutine DTPT01 (uplo, diag, n, ap, ainvp, rcond, work, resid)
    DTPT01

🎀 Function/Subroutine Documentation 🎀

subroutine DTPT01 (character uplo, character diag, integer n, double
    precision, dimension( * ) ap, double precision, dimension( * ) ainvp,
    double precision rcond, double precision, dimension( * ) work, double
    precision resid)
    DTPT01

Purpose

So the whole point, bestie: DTPT01 computes the residual for a triangular matrix A times its inverse when A is stored in packed format:

RESID = norm(A*AINV - I) / ( N * norm(A) * norm(AINV) * EPS ),

where EPS is the machine epsilon. Periodt. ✨

Parameters

• UPLO — UPLO is CHARACTER*1. Specifies whether the matrix A is upper or lower triangular.
  • = 'U': Upper triangular
  • = 'L': Lower triangular
• DIAG — DIAG is CHARACTER*1. Specifies whether or not the matrix A is unit triangular.
  • = 'N': Non-unit triangular
  • = 'U': Unit triangular
• N — N is INTEGER. The order of the matrix A. N >= 0.
• AP — AP is DOUBLE PRECISION array, dimension (N*(N+1)/2). The original 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((j-1)*j/2 + i) = A(i,j) for 1<=i<=j;
  • if UPLO = 'L', AP((j-1)*(n-j) + j*(j+1)/2 + i-j) = A(i,j) for j<=i<=n.
• AINVP — AINVP is DOUBLE PRECISION array, dimension (N*(N+1)/2). On entry, the (triangular) inverse of the matrix A, packed columnwise in a linear array as in AP. On exit, the contents of AINVP are destroyed. 💀 Yes, destroyed — don't get attached, bestie.
• RCOND — RCOND is DOUBLE PRECISION. The reciprocal condition number of A, computed as 1/(norm(A) * norm(AINV)).
• WORK — WORK is DOUBLE PRECISION array, dimension (N).
• RESID — RESID is DOUBLE PRECISION. norm(A*AINV - I) / ( N * norm(A) * norm(AINV) * EPS ).

Author

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

Definition at line 107 of file dtpt01.f.

Author

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Okay that's the whole page, bestie. This icon is LAPACK Version 3.12.0, and the footer source/page stamp is /home/abui...IN/dtpt01.f(3) — slay responsibly. 💖✨