SRC/ssyrfs.f(3)

✨ NAME ✨

okay so this is the page for SRC/ssyrfs.f(3), from the Library Functions Manual, and the NAME section is literally just SRC/ssyrfs.f — lowkey iconic that it keeps it that simple 💅

🧚 SYNOPSIS 🧚

Functions/Subroutines

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

💖 Function/Subroutine Documentation 💖

       subroutine ssyrfs (character uplo, integer n, integer nrhs, real, dimension(
           lda, * ) a, integer lda, real, dimension( ldaf, * ) af, integer ldaf,
           integer, dimension( * ) ipiv, real, dimension( ldb, * ) b, integer ldb,
           real, dimension( ldx, * ) x, integer ldx, real, dimension( * ) ferr,
           real, dimension( * ) berr, real, dimension( * ) work, integer,
           dimension( * ) iwork, integer info)
           SSYRFS

🎯 Purpose 🎯

bestie, SSYRFS is the subroutine that improves the computed solution to a system of linear equations when the coefficient matrix is symmetric indefinite, and it also provides error bounds and backward error estimates for the solution. slay, honestly ✨

💅 Parameters 💅

• UPLO — is CHARACTER*1. the vibe check:
  • = 'U': upper triangle of A is stored;
  • = 'L': lower triangle of A is stored.
• N — is INTEGER; the order of the matrix A. N >= 0.
• NRHS — is INTEGER; the number of right hand sides, i.e., the number of columns of the matrices B and X. NRHS >= 0.
• A — is REAL 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 — is INTEGER; the leading dimension of the array A. LDA >= max(1,N).
• AF — is REAL array, dimension (LDAF,N); the factored form of the matrix A. AF contains the block diagonal matrix D and the multipliers used to obtain the factor U or L from the factorization A = U*D*U**T or A = L*D*L**T as computed by SSYTRF.
• LDAF — is INTEGER; the leading dimension of the array AF. LDAF >= max(1,N).
• IPIV — is INTEGER array, dimension (N); details of the interchanges and the block structure of D as determined by SSYTRF.
• B — is REAL array, dimension (LDB,NRHS); the right hand side matrix B.
• LDB — is INTEGER; the leading dimension of the array B. LDB >= max(1,N).
• X — is REAL array, dimension (LDX,NRHS); on entry, the solution matrix X, as computed by SSYTRS. On exit, the improved solution matrix X.
• LDX — is INTEGER; the leading dimension of the array X. LDX >= max(1,N).
• FERR — is REAL 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 — is REAL 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 — is REAL array, dimension (3*N).
• IWORK — is INTEGER array, dimension (N).
• INFO — is 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.

👑 Author 👑

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

Definition at line 189 of file ssyrfs.f.

📝 Author (the generated one) 📝

Generated automatically by Doxygen for LAPACK from the source code.

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okay that's the whole page, bestie 🫶 the footer vibes are LAPACK Version 3.12.0 and SRC/ssyrfs.f(3) — no date is listed in the original footer, so that's the sign-off, mwah 💋✨