BLAS/SRC/dnrm2.f90(3)

💅 BLAS/SRC/dnrm2.f90(3) — DNRM2 said “norm girl summer” ✨

okay so bestie, this is the Library Functions Manual page for BLAS/SRC/dnrm2.f90(3), and it is literally about DNRM2 returning the euclidean norm. The math is mathing, the vibe is immaculate, and yes we are keeping every single detail. 🫶

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🌸 NAME 🌸

BLAS/SRC/dnrm2.f90 — the file, the icon, the main character. 💖

🌈 SYNOPSIS 🌈

Functions/Subroutines:

• real(wp) function dnrm2 (n, x, incx) — DNRM2

💫 Function/Subroutine Documentation 💫

🎀 real(wp) function dnrm2 (integer n, real(wp), dimension(*) x, integer incx) 🎀

DNRM2. periodt. 💅

🌟 Purpose

DNRM2 returns the euclidean norm of a vector via the function name, so that

DNRM2 := sqrt( x'*x )

💖 Parameters 💖

• N — is INTEGER; number of elements in input vector(s). 🧮
• X — is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ). 📦
• INCX — is INTEGER; storage spacing between elements of X.

and the INCX lore is giving very specific, bestie:

• If INCX > 0, X(1+(i-1)*INCX) = x(i) for 1 <= i <= n
• If INCX < 0, X(1-(n-i)*INCX) = x(i) for 1 <= i <= n
• If INCX = 0, x isn't a vector so there is no need to call this subroutine. If you call it anyway, it will count x(1) in the vector norm N times. 💀 no cap, that is the warning.

👑 Author

Edward Anderson, Lockheed Martin

🎂 Date

August 2016

🫶 Contributors:

Weslley Pereira, University of Colorado Denver, USA

🔥 Further Details:

• Anderson E. (2017) — Algorithm 978: Safe Scaling in the Level 1 BLAS — ACM Trans Math Softw 44:1--28 — https://doi.org/10.1145/3061665
• Blue, James L. (1978) — A Portable Fortran Program to Find the Euclidean Norm of a Vector — ACM Trans Math Softw 4:15--23 — https://doi.org/10.1145/355769.355771

Definition at line 88 of file dnrm2.f90.

🤖 Author

Generated automatically by Doxygen for LAPACK from the source code.

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💌 mwah, bestie — this page is from LAPACK Version 3.12.0, page BLAS/SRC/dnrm2.f90(3), dated August 2016. slay. 💖