dlassq.f(3)

📦 version 3.9.0, in centos-stream 9

🦋 dlassq.f — LAPACK’s scaled sum-of-squares bestie 🦋

okay so bestie, this is the LAPACK manual page for dlassq.f, and she is here to update a sum of squares represented in scaled form. no cap.

🌸 NAME 🌸

dlassq.f

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

  • subroutine dlassq (N, X, INCX, SCALE, SUMSQ) — DLASSQ updates a sum of squares represented in scaled form.

💖 Function/Subroutine Documentation 💖

subroutine dlassq (integer N, double precision, dimension( * ) X, integer
       INCX, double precision SCALE, double precision SUMSQ)

DLASSQ updates a sum of squares represented in scaled form.

🔥 Purpose 🔥

okay so DLASSQ returns the values scl and smsq such that

( scl**2 )*smsq = x( 1 )**2 +...+ x( n )**2 + ( scale**2 )*sumsq,

where x( i ) = X( 1 + ( i - 1 )*INCX ). The value of sumsq is assumed to be non-negative, and scl returns the value

scl = max( scale, abs( x( i ) ) ).

scale and sumsq must be supplied in SCALE and SUMSQ, and scl and smsq are overwritten on SCALE and SUMSQ respectively.

The routine makes only one pass through the vector x — literally one pass, no extra laps, periodt.

🍓 Parameters 🍓

  • N — N is INTEGER. The number of elements to be used from the vector X.
  • X — X is DOUBLE PRECISION array, dimension (N). The vector for which a scaled sum of squares is computed. x( i ) = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n.
  • INCX — INCX is INTEGER. The increment between successive values of the vector X. INCX > 0.
  • SCALE — SCALE is DOUBLE PRECISION. On entry, the value scale in the equation above. On exit, SCALE is overwritten with scl, the scaling factor for the sum of squares.
  • SUMSQ — SUMSQ is DOUBLE PRECISION. On entry, the value sumsq in the equation above. On exit, SUMSQ is overwritten with smsq, the basic sum of squares from which scl has been factored out.

👑 Author 👑

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

🌈 Date 🌈

December 2016

Definition at line 105 of file dlassq.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

Version 3.8.0 · Date Tue Nov 14 2017 · Page dlassq.f(3) — byeee bestie, go update that sum of squares with main character energy! 💅✨🦋

📦 where this page comes from