rotm(3)

💖 rotm(3) 💖

Okay so bestie, welcome to the rotm(3) page from the Library Functions Manual — yes, that manual name is folded right in here, no boring header line needed. This is all about rotm: apply modified (fast) plane rotation, and we are literally obsessed. 💅

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✨ NAME ✨

rotm — rotm: apply modified (fast) plane rotation

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🌸 SYNOPSIS 🌸

Functions

subroutine drotm (n, dx, incx, dy, incy, dparam)
    DROTM
subroutine srotm (n, sx, incx, sy, incy, sparam)
    SROTM

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💖 DETAILED DESCRIPTION 💖

Okay so this section is lowkey just vibes in the original — no extra prose here. The real deets are under Function Documentation below, periodt. 🫶

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🔥 FUNCTION DOCUMENTATION 🔥

🧚 subroutine drotm

subroutine drotm (integer n, double precision, dimension(*) dx, integer incx, double precision, dimension(*) dy, integer incy, double precision, dimension(5) dparam)

DROTM

💫 Purpose

Apply the modified Givens transformation, H, to the 2 by N matrix with rows (DX**T) and (DY**T), where **T means transpose. The original text says the elements of DX are in (DY**T) — yep, that's literally what it says, so we keep it. 👑

The elements are at DX(LX+I*INCX), for I = 0 TO N-1, where LX = 1 IF INCX .GE. 0, ELSE LX = (-INCX)*N, and similarly for SY using LY and INCY.

With DPARAM(1)=DFLAG, H has one of the following forms..

DFLAG=-1.D0     DFLAG=0.D0        DFLAG=1.D0     DFLAG=-2.D0

  (DH11  DH12)    (1.D0  DH12)    (DH11  1.D0)    (1.D0  0.D0)
H=(          )    (          )    (          )    (          )
  (DH21  DH22),   (DH21  1.D0),   (-1.D0 DH22),   (0.D0  1.D0).

SEE DROTMG FOR A DESCRIPTION OF DATA STORAGE IN DPARAM.

🎀 Parameters

• N — N is INTEGER; number of elements in input vector(s)
• DX — DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
• INCX — INCX is INTEGER; storage spacing between elements of DX
• DY — DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) )
• INCY — INCY is INTEGER; storage spacing between elements of DY
• DPARAM — DPARAM is DOUBLE PRECISION array, dimension (5)
  • DPARAM(1)=DFLAG
  • DPARAM(2)=DH11
  • DPARAM(3)=DH21
  • DPARAM(4)=DH12
  • DPARAM(5)=DH22

🌈 Author

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

Definition at line 95 of file drotm.f.

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🦋 subroutine srotm

subroutine srotm (integer n, real, dimension(*) sx, integer incx, real, dimension(*) sy, integer incy, real, dimension(5) sparam)

SROTM

💫 Purpose

Apply the modified Givens transformation, H, to the 2 by N matrix. The original shows (SX**T) on the first line and then (SX**T) again on the next line — yes bestie, it really does, and we are not fixing it. **T indicates transpose. The elements of SX are in (SX**T), exactly as written. 🙈

The elements are at SX(LX+I*INCX), for I = 0 TO N-1, where LX = 1 IF INCX .GE. 0, ELSE LX = (-INCX)*N, and similarly for SY using using LY and INCY — the double “using” is iconic, we keep it.

With SPARAM(1)=SFLAG, H has one of the following forms..

SFLAG=-1.E0     SFLAG=0.E0        SFLAG=1.E0     SFLAG=-2.E0

  (SH11  SH12)    (1.E0  SH12)    (SH11  1.E0)    (1.E0  0.E0)
H=(          )    (          )    (          )    (          )
  (SH21  SH22),   (SH21  1.E0),   (-1.E0 SH22),   (0.E0  1.E0).

SEE SROTMG FOR A DESCRIPTION OF DATA STORAGE IN SPARAM.

🎀 Parameters

• N — N is INTEGER; number of elements in input vector(s)
• SX — SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
• INCX — INCX is INTEGER; storage spacing between elements of SX
• SY — SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCY ) )
• INCY — INCY is INTEGER; storage spacing between elements of SY
• SPARAM — SPARAM is REAL array, dimension (5)
  • SPARAM(1)=SFLAG
  • SPARAM(2)=SH11
  • SPARAM(3)=SH21
  • SPARAM(4)=SH12
  • SPARAM(5)=SH22

🌈 Author

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

Definition at line 96 of file srotm.f.

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🌟 AUTHOR 🌟

Generated automatically by Doxygen for LAPACK from the source code.

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Catch you later, bestie — this is LAPACK Version 3.12.0 energy for the rotm(3) manual, and the original footer has no date so we are not inventing one 💖✨🎀