SRC/cspmv.f(3)

💖 SRC/cspmv.f(3) 💖

bestie, this is a page from the Library Functions Manual, and it's all about the Fortran subroutine cspmv. it's giving "complex symmetric packed matrix-vector product" and honestly? iconic. 🦋✨

---

🌸 NAME 🌸

SRC/cspmv.f

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

• subroutine cspmv (uplo, n, alpha, ap, x, incx, beta, y, incy) — CSPMV computes a matrix-vector product for complex vectors using a complex symmetric packed matrix

👑 Function/Subroutine Documentation 👑

subroutine cspmv (character uplo, integer n, complex alpha, complex,
    dimension( * ) ap, complex, dimension( * ) x, integer incx, complex
    beta, complex, dimension( * ) y, integer incy)

CSPMV computes a matrix-vector product for complex vectors using a complex symmetric packed matrix

💅 Purpose 💅

okay so CSPMV performs the matrix-vector operation:

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

where alpha and beta are scalars, x and y are n element vectors, and A is an n by n symmetric matrix, supplied in packed form. no cap, that's the whole vibe. 💜

🌈 Parameters 🌈

• UPLO — UPLO is CHARACTER*1. On entry, UPLO specifies whether the upper or lower triangular part of the matrix A is supplied in the packed array AP as follows:
  • UPLO = 'U' or 'u' — The upper triangular part of A is supplied in AP.
  • UPLO = 'L' or 'l' — The lower triangular part of A is supplied in AP.

Unchanged on exit.

• N — N is INTEGER. On entry, N specifies the order of the matrix A. N must be at least zero. Unchanged on exit.
• ALPHA — ALPHA is COMPLEX. On entry, ALPHA specifies the scalar alpha. Unchanged on exit.
• AP — AP is COMPLEX array, dimension at least ( ( N*( N + 1 ) )/2 ). Before entry, with UPLO = 'U' or 'u', the array AP must contain the upper triangular part of the symmetric matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 ) respectively, and so on. Before entry, with UPLO = 'L' or 'l', the array AP must contain the lower triangular part of the symmetric matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 ) respectively, and so on. Unchanged on exit.
• X — X is COMPLEX array, dimension at least ( 1 + ( N - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the N-element vector x. Unchanged on exit.
• INCX — INCX is INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero. Unchanged on exit.
• BETA — BETA is COMPLEX. 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 — Y is COMPLEX array, dimension at least ( 1 + ( N - 1 )*abs( INCY ) ). Before entry, the incremented array Y must contain the n element vector y. On exit, Y is overwritten by the updated vector y.
• INCY — INCY is INTEGER. On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. Unchanged on exit.

🫶 Author 🫶

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 150 of file cspmv.f.

⭐ Author ⭐

Generated automatically by Doxygen for LAPACK from the source code.

---

that's the whole page, bestie — brought to you by LAPACK Version 3.12.0 and the source file SRC/cspmv.f(3) 💖✨🫶