CLASSQ(3)

📦 version 3.12.0, in opensuse-leap 16.0

💅 NAME

okay so bestie, this whole page is about one file, and it lives at /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/classq.f90 — that's the whole NAME section, no cap. it's a man page from the Library Functions Manual, and the page itself is classq.f90(3). 💖

✨ SYNOPSIS ✨

🦋 Functions/Subroutines

  • subroutine CLASSQ (n, x, incx, scale, sumsq) — CLASSQ updates a sum of squares represented in scaled form. that's literally the whole job, and it ate. 👑

🎀 Function/Subroutine Documentation 🎀

subroutine CLASSQ (integer n, complex(wp), dimension(*) x, integer incx,
    real(wp) scale, real(wp) sumsq)

CLASSQ updates a sum of squares represented in scaled form. iconic behaviour, honestly. 🌸

💜 Purpose

so here's the vibe check: CLASSQ returns the values scale_out and sumsq_out such that

(scale_out**2)*sumsq_out = x( 1 )**2 +...+ x( n )**2 + (scale**2)*sumsq,

where x( i ) = X( 1 + ( i - 1 )*INCX ). and listen — the value of sumsq is assumed to be non-negative. that's a whole assumption, bestie, don't come at it with negative numbers. 🙈

scale and sumsq must be supplied in SCALE and SUMSQ, and scale_out and sumsq_out are overwritten on SCALE and SUMSQ respectively. so yeah, it's giving in-place, main character energy. ✨

🌈 Parameters

  • N — N is INTEGER. the number of elements to be used from the vector x. 🍓
  • X — X is COMPLEX array, dimension (1+(N-1)*abs(INCX)). the vector for which a scaled sum of squares is computed, where x( i ) = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n. 💖
  • INCX — INCX is INTEGER. the increment between successive values of the vector x, and the details matter so here they are exactly:
    • 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. 💀 yeah. it'll just do that. you've been warned.
  • SCALE — SCALE is REAL. on entry, the value scale in the equation above. on exit, SCALE is overwritten by scale_out, the scaling factor for the sum of squares. 🧚
  • SUMSQ — SUMSQ is REAL. on entry, the value sumsq in the equation above. on exit, SUMSQ is overwritten by sumsq_out, the basic sum of squares from which scale_out has been factored out. 🫶

👑 Author

Edward Anderson, Lockheed Martin. legend behaviour, fr fr.

🌟 Contributors:

Weslley Pereira, University of Colorado Denver, USA — and — Nick Papior, Technical University of Denmark, DK. the squad. 🫶

⭐ Further Details:

the receipts, bestie, all cited and everything:

Definition at line 123 of file classq.f90. 📍

💫 Author

Generated automatically by Doxygen for LAPACK from the source code. not a human, just a little robot doing its best. 🤖✨

and that's the whole page, bestie — this one's LAPACK Version 3.12.0, and the footer path is /home/abui.../classq.f90(3). go forth and scale your sums of squares responsibly. mwah. 💅🎀🦋

📦 where this page comes from