DPORFS(3)

💖 DPORFS(3) — Library Functions Manual 💖

🌸 NAME 🌸

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

Bestie, that’s the file this entire page is about. 💅

🦋 SYNOPSIS 🦋

✨ Functions/Subroutines ✨

       subroutine DPORFS (uplo, n, nrhs, a, lda, af, ldaf, b, ldb, x, ldx,
           ferr, berr, work, iwork, info)
           DPORFS

🌟 Function/Subroutine Documentation 🌟

       subroutine DPORFS (character uplo, integer n, integer nrhs, double
       precision, dimension( lda, * ) a, integer lda, double precision,
       dimension( ldaf, * ) af, integer ldaf, double precision, dimension( ldb,
       * ) b, integer ldb, double precision, dimension( ldx, * ) x, integer
       ldx, double precision, dimension( * ) ferr, double precision, dimension(
       * ) berr, double precision, dimension( * ) work, integer, dimension( * )
       iwork, integer info)
       DPORFS

💖 Purpose 💖

Okay so DPORFS improves the computed solution to a system of linear equations when the coefficient matrix is symmetric positive definite, and it provides error bounds and backward error estimates for the solution. Slay. 💖

🍓 Parameters 🍓

• UPLO — Type: CHARACTER*1. = 'U': the upper triangle of A is stored; = 'L': the lower triangle of A is stored. 🦋
• N — Type: INTEGER. The order of the matrix A. N >= 0.
• NRHS — Type: INTEGER. The number of right hand sides, i.e., the number of columns of the matrices B and X. NRHS >= 0.
• A — Type: DOUBLE PRECISION array, dimension (LDA,N). The symmetric matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced.
• LDA — Type: INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• AF — Type: DOUBLE PRECISION array, dimension (LDAF,N). The triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, as computed by DPOTRF.
• LDAF — Type: INTEGER. The leading dimension of the array AF. LDAF >= max(1,N).
• B — Type: DOUBLE PRECISION array, dimension (LDB,NRHS). The right hand side matrix B.
• LDB — Type: INTEGER. The leading dimension of the array B. LDB >= max(1,N).
• X — Type: DOUBLE PRECISION array, dimension (LDX,NRHS). On entry, the solution matrix X, as computed by DPOTRS. On exit, the improved solution matrix X.
• LDX — Type: INTEGER. The leading dimension of the array X. LDX >= max(1,N).
• FERR — Type: DOUBLE PRECISION array, dimension (NRHS). The estimated forward error bound for each solution vector X(j) (the j-th column of the solution matrix X). If XTRUE is the true solution corresponding to X(j), FERR(j) is an estimated upper bound for the magnitude of the largest element in (X(j) - XTRUE) divided by the magnitude of the largest element in X(j). The estimate is as reliable as the estimate for RCOND, and is almost always a slight overestimate of the true error.
• BERR — Type: DOUBLE PRECISION array, dimension (NRHS). The componentwise relative backward error of each solution vector X(j) (i.e., the smallest relative change in any element of A or B that makes X(j) an exact solution).
• WORK — Type: DOUBLE PRECISION array, dimension (3*N).
• IWORK — Type: INTEGER array, dimension (N).
• INFO — Type: INTEGER. = 0: successful exit. < 0: if INFO = -i, the i-th argument had an illegal value.

🧚 Internal Parameters 🧚

ITMAX is the maximum number of steps of iterative refinement. Periodt. 💅

👑 Author 👑

Shoutout to the author squad:

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

📍 Definition at line 181 of file dporfs.f. 📍

Yep, this routine is defined at line 181 of dporfs.f. 🎀

🎀 Author 🎀

Generated automatically by Doxygen for LAPACK from the source code.

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Sign-off vibes: LAPACK, Version 3.12.0, source path /home/abui...RC/dporfs.f(3) — that’s the footer energy, bestie. Byeee 💖✨