BLAS/SRC/sgemv.f(3)

💖 NAME 💖

BLAS/SRC/sgemv.f — bestie, this is the file you're looking at, and it's literally the home of the SGEMV routine. iykyk ✨

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🦋 SYNOPSIS 🦋

Functions/Subroutines

• subroutine sgemv (trans, m, n, alpha, a, lda, x, incx, beta, y, incy) — aka SGEMV 👑

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🌸 Function/Subroutine Documentation 🌸

subroutine sgemv (character trans, integer m, integer n, real alpha, real, dimension(lda,*) a, integer lda, real, dimension(*) x, integer incx, real beta, real, dimension(*) y, integer incy)

okay so this is SGEMV and she's iconic 💅

🎀 Purpose 🎀

SGEMV performs one of the matrix-vector operations

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

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

✨ Parameters ✨

• TRANS — bestie, TRANS is CHARACTER*1. On entry, TRANS specifies the operation to be performed as follows:
  • TRANS = 'N' or 'n' → y := alpha*A*x + beta*y.
  • TRANS = 'T' or 't' → y := alpha*A**T*x + beta*y.
  • TRANS = 'C' or 'c' → y := alpha*A**T*x + beta*y.
• M — M is INTEGER. On entry, M specifies the number of rows of the matrix A. M must be at least zero. no cap. 🫶
• N — N is INTEGER. On entry, N specifies the number of columns of the matrix A. N must be at least zero. 💜
• ALPHA — ALPHA is REAL. On entry, ALPHA specifies the scalar alpha. 🍓
• A — A is REAL array, dimension ( LDA, N ). Before entry, the leading m by n part of the array A must contain the matrix of coefficients.
• LDA — LDA is INTEGER. On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA must be at least max( 1, m ).
• X — X is REAL array, dimension at least
  • ( 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. 💫

• INCX — INCX is INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero. ⚠️ like, do NOT pass zero bestie, that's not the vibe.
• BETA — BETA is REAL. On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input. lowkey convenient ✨
• Y — Y is REAL array, dimension at least
  • ( 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 — INCY is INTEGER. On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. 🚨 again: not zero!!

👑 Author 👑

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

🔥 Further Details: 🔥

Level 2 Blas routine.
The vector and matrix arguments are not referenced when N = 0, or M = 0

-- Written on 22-October-1986.
   Jack Dongarra, Argonne National Lab.
   Jeremy Du Croz, Nag Central Office.
   Sven Hammarling, Nag Central Office.
   Richard Hanson, Sandia National Labs.

Definition at line 157 of file sgemv.f. 💅

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. yes bestie, the robots wrote this part 🤖✨

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and that's the whole page fr fr — shoutout to LAPACK Version 3.12.0, dated Tue Nov 28 2023 12:08:41, from the one and only BLAS/SRC/sgemv.f(3). slay, ate, no crumbs left 💖🎀🦋🌸💅🫶👑