TESTING/LIN/dlarhs.f(3)

💅 TESTING/LIN/dlarhs.f(3) 💅

Library Functions Manual, but make it group-chat energy. This is the whole page for TESTING/LIN/dlarhs.f, and yes bestie, it’s giving Fortran testing realness. 🫶

🌸 NAME 🌸

TESTING/LIN/dlarhs.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

       subroutine dlarhs (path, xtype, uplo, trans, m, n, kl, ku, nrhs, a, lda,
           x, ldx, b, ldb, iseed, info)
           DLARHS

💅 Function/Subroutine Documentation 💅

   subroutine dlarhs (character*3 path, character xtype, character uplo,
       character trans, integer m, integer n, integer kl, integer ku, integer
       nrhs, double precision, dimension( lda, * ) a, integer lda, double
       precision, dimension( ldx, * ) x, integer ldx, double precision,
       dimension( ldb, * ) b, integer ldb, integer, dimension( 4 ) iseed,
       integer info)
       DLARHS

🎯 Purpose 🎯

Okay so DLARHS is the main character that chooses a set of NRHS random solution vectors and sets up the right hand sides for the linear system:

op(A) * X = B,

where op(A) = A or A**T, depending on TRANS. Periodt. 💖

🧸 Parameters 🧸

• PATH — PATH is CHARACTER*3. It tells you the type of the real matrix A. It may be given in any combination of upper and lower case. Valid types include:
  • xGE: General m x n matrix
  • xGB: General banded matrix
  • xPO: Symmetric positive definite, 2-D storage
  • xPP: Symmetric positive definite packed
  • xPB: Symmetric positive definite banded
  • xSY: Symmetric indefinite, 2-D storage
  • xSP: Symmetric indefinite packed
  • xSB: Symmetric indefinite banded
  • xTR: Triangular
  • xTP: Triangular packed
  • xTB: Triangular banded
  • xQR: General m x n matrix
  • xLQ: General m x n matrix
  • xQL: General m x n matrix
  • xRQ: General m x n matrix where the leading character indicates the precision. Slay. ✨
• XTYPE — XTYPE is CHARACTER*1. It specifies how the exact solution X will be determined:
  • = 'N': New solution; generate a random X.
  • = 'C': Computed; use value of X on entry.
• UPLO — UPLO is CHARACTER*1. It specifies whether the upper or lower triangular part of the matrix A is stored, if A is symmetric:
  • = 'U': Upper triangular
  • = 'L': Lower triangular
• TRANS — TRANS is CHARACTER*1. Used only if A is nonsymmetric; specifies the operation applied to the matrix A:
  • = 'N': B := A * X (No transpose)
  • = 'T': B := A**T * X (Transpose)
  • = 'C': B := A**H * X (Conjugate transpose = Transpose)
• M — M is INTEGER. The number of rows of the matrix A. M >= 0.
• N — N is INTEGER. The number of columns of the matrix A. N >= 0.
• KL — KL is INTEGER. Used only if A is a band matrix; specifies the number of subdiagonals of A if A is a general band matrix or if A is symmetric or triangular and UPLO = 'L'; specifies the number of superdiagonals of A if A is symmetric or triangular and UPLO = 'U'. 0 <= KL <= M-1.
• KU — KU is INTEGER. Used only if A is a general band matrix or if A is triangular.

If PATH = xGB, specifies the number of superdiagonals of A, and 0 <= KU <= N-1.

If PATH = xTR, xTP, or xTB, specifies whether or not the matrix has unit diagonal:

• = 1: matrix has non-unit diagonal (default)
• = 2: matrix has unit diagonal

• NRHS — NRHS is INTEGER. The number of right hand side vectors in the system A*X = B.
• A — A is DOUBLE PRECISION array, dimension (LDA,N). The test matrix whose type is given by PATH.
• LDA — LDA is INTEGER. The leading dimension of the array A.
  • If PATH = xGB, LDA >= KL+KU+1.
  • If PATH = xPB, xSB, xHB, or xTB, LDA >= KL+1.
  • Otherwise, LDA >= max(1,M).
• X — X is an input or output DOUBLE PRECISION array, dimension (LDX,NRHS). On entry, if XTYPE = 'C' (for 'Computed'), then X contains the exact solution to the system of linear equations. On exit, if XTYPE = 'N' (for 'New'), then X is initialized with random values.
• LDX — LDX is INTEGER. The leading dimension of the array X. If TRANS = 'N', LDX >= max(1,N); if TRANS = 'T', LDX >= max(1,M).
• B — B is DOUBLE PRECISION array, dimension (LDB,NRHS). The right hand side vector(s) for the system of equations, computed from B = op(A) * X, where op(A) is determined by TRANS.
• LDB — LDB is INTEGER. The leading dimension of the array B. If TRANS = 'N', LDB >= max(1,M); if TRANS = 'T', LDB >= max(1,N).
• ISEED — ISEED is INTEGER array, dimension (4). The seed vector for the random number generator (used in DLATMS). Modified on exit.
• 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 203 of file dlarhs.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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