BLAS/SRC/dspr2.f(3)

💅 dspr2 — symmetric rank 2, packed-matrix edition ✨

okay so bestie, this is the BLAS/SRC/dspr2.f(3) page from the Library Functions Manual, and it's giving "small BLAS routine, main character energy." We're talking about dspr2 here. Let's get into it.

🏷️ NAME

BLAS/SRC/dspr2.f — that's the file this page is documenting. Periodt.

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✨ SYNOPSIS ✨

Functions/Subroutines

subroutine dspr2 (uplo, n, alpha, x, incx, y, incy, ap)
    DSPR2

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🧚 Function/Subroutine Documentation

subroutine dspr2 (character uplo, integer n, double precision alpha, double precision, dimension(*) x, integer incx, double precision, dimension(*) y, integer incy, double precision, dimension(*) ap)
    DSPR2

🎯 Purpose

DSPR2 performs the symmetric rank 2 operation

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

where alpha is a scalar, x and y are n element vectors and A is an n by n symmetric matrix, supplied in packed form.

🌸 Parameters

• 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.
• N — is INTEGER. On entry, N specifies the order of the matrix A. N must be at least zero.
• ALPHA — is DOUBLE PRECISION. On entry, ALPHA specifies the scalar alpha.
• X — is DOUBLE PRECISION array, dimension at least ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element vector x.
• INCX — is INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero.
• Y — is DOUBLE PRECISION array, dimension at least ( 1 + ( n - 1 )*abs( INCY ) ). Before entry, the incremented array Y must contain the n element vector y.
• INCY — is INTEGER. On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.
• AP — is DOUBLE PRECISION 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. On exit, the array AP is overwritten by the upper triangular part of the updated matrix.
  • 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. On exit, the array AP is overwritten by the lower triangular part of the updated matrix.

👑 Author

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

🔥 Further Details

• Level 2 Blas routine.
• -- 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

Definition at line 141 of file dspr2.f.

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🤖 Author

Generated automatically by Doxygen for LAPACK from the source code.

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LAPACK Version 3.12.0 vibes, from BLAS/SRC/dspr2.f(3) — footer sign-off complete, bestie. 💖