/home/abui...la_gbamv.f(3)

💖 /home/abui...la_gbamv.f(3) 💖

Library Functions Manual, bestie — folding that manual name in right here instead of doing a whole header line. This page is about CLA_GBAMV, and yes the title is literally a build path. We’re making it cute anyway 💅.

🎀 NAME 🎀

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

✨ SYNOPSIS ✨

Functions/Subroutines — incoming, bestie:

subroutine CLA_GBAMV (trans, m, n, kl, ku, alpha, ab, ldab, x, incx,
    beta, y, incy)

CLA_GBAMV performs a matrix-vector operation to calculate error bounds. That’s the whole vibe.

💅 Function/Subroutine Documentation 💅

subroutine CLA_GBAMV (integer trans, integer m, integer n, integer kl,
    integer ku, real alpha, complex, dimension( ldab, * ) ab, integer ldab,
    complex, dimension( * ) x, integer incx, real beta, real, dimension( * )
    y, integer incy)

CLA_GBAMV performs a matrix-vector operation to calculate error bounds. Iconic.

🦋 Purpose

CLA_GBAMV does one of these matrix-vector operations:

y := alpha*abs(A)*abs(x) + beta*abs(y),
or   y := alpha*abs(A)**T*abs(x) + beta*abs(y),

where alpha and beta are scalars, x and y are vectors, and A is an m by n matrix.

This function is primarily used in calculating error bounds. To protect against underflow during evaluation, components in the resulting vector are perturbed away from zero by (N+1) times the underflow threshold. To prevent unnecessarily large errors for block-structure embedded in general matrices, zero components are not perturbed. A zero entry is considered if all multiplications involved in computing that entry have at least one zero multiplicand. No cap.

🌸 Parameters 🌸

• TRANS — INTEGER. On entry, TRANS specifies the operation to be performed as follows:
  • BLAS_NO_TRANS — y := alpha*abs(A)*abs(x) + beta*abs(y)
  • BLAS_TRANS — y := alpha*abs(A**T)*abs(x) + beta*abs(y)
  • BLAS_CONJ_TRANS — y := alpha*abs(A**T)*abs(x) + beta*abs(y) Unchanged on exit.
• M — INTEGER. On entry, M specifies the number of rows of the matrix A. M must be at least zero. Unchanged on exit.
• N — INTEGER. On entry, N specifies the number of columns of the matrix A. N must be at least zero. Unchanged on exit.
• KL — INTEGER. The number of subdiagonals within the band of A. KL >= 0.
• KU — INTEGER. The number of superdiagonals within the band of A. KU >= 0.
• ALPHA — REAL. On entry, ALPHA specifies the scalar alpha. Unchanged on exit.
• AB — COMPLEX array, dimension (LDAB,n). Before entry, the leading m by n part of the array AB must contain the matrix of coefficients. Unchanged on exit.
• LDAB — INTEGER. On entry, LDAB specifies the first dimension of AB as declared in the calling (sub) program. LDAB must be at least max( 1, m ). Unchanged on exit.
• X — COMPLEX array, dimension

( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n'
and at least
( 1 + ( m - 1 )*abs( INCX ) ) otherwise.

Before entry, the incremented array X must contain the vector x. Unchanged on exit.

• INCX — INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero. Unchanged on exit.
• BETA — REAL. On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input. Unchanged on exit.
• Y — REAL array, dimension

( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n'
and at least
( 1 + ( n - 1 )*abs( INCY ) ) otherwise.

Before entry with BETA non-zero, the incremented array Y must contain the vector y. On exit, Y is overwritten by the updated vector y. If either m or n is zero, then Y not referenced and the function performs a quick return.

• INCY — INTEGER. On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. Unchanged on exit.

Level 2 Blas routine.

🌈 Author

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

Definition at line 186 of file cla_gbamv.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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Byeee, bestie 💅 — this page is LAPACK Version 3.12.0, and the page path is /home/abui...la_gbamv.f(3). Periodt ✨