SRC/dlarf1l.f(3)

💖 NAME

Okay bestie, this page is SRC/dlarf1l.f(3) from the Library Functions Manual — and it's all about the dlarf1l subroutine. No cap, it's giving tiny file, big linear algebra energy. 🫶

✨ SYNOPSIS

🧚 Functions/Subroutines

subroutine dlarf1l (side, m, n, v, incv, tau, c, ldc, work)
    DLARF1L applies an elementary reflector to a general rectangular

🫶 Function/Subroutine Documentation

Here's the full signature, copied exactly so nobody has to type it from memory:

subroutine dlarf1l (character side, integer m, integer n, double precision,
    dimension( * ) v, integer incv, double precision tau, double precision,
    dimension( ldc, * ) c, integer ldc, double precision, dimension( * )
    work)

The one-line description is literally: DLARF1L applies an elementary reflector to a general rectangular.

🎀 Purpose

So the actual glow-up is this: DLARF1L applies a real elementary reflector H to a real m by n matrix C, from either the left or the right. H is represented in the form:

H = I - tau * v * v**T

where tau is a real scalar and v is a real vector.

If tau = 0, then H is taken to be the unit matrix. That's the whole vibe. ✨

👑 Parameters

Parameters time, and yes, every single one is here:

• SIDE — SIDE is CHARACTER*1. = 'L': form H * C; = 'R': form C * H. 💅
• M — M is INTEGER. The number of rows of the matrix C.
• N — N is INTEGER. The number of columns of the matrix C.
• V — V is DOUBLE PRECISION array, dimension (1 + (M-1)*abs(INCV)) if SIDE = 'L' or (1 + (N-1)*abs(INCV)) if SIDE = 'R'. This is the vector v in the representation of H. V is not used if TAU = 0.
• INCV — INCV is INTEGER. The increment between elements of v. INCV <> 0.
• TAU — TAU is DOUBLE PRECISION. The value tau in the representation of H.
• C — C is DOUBLE PRECISION array, dimension (LDC,N). On entry, the m by n matrix C. On exit, C is overwritten by the matrix H * C if SIDE = 'L', or C * H if SIDE = 'R'.
• LDC — LDC is INTEGER. The leading dimension of the array C. LDC >= max(1,M).
• WORK — WORK is DOUBLE PRECISION array, dimension (N) if SIDE = 'L' or (M) if SIDE = 'R'.

📝 Author

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

Definition at line 125 of file dlarf1l.f.

🪄 Author

Generated automatically by Doxygen for LAPACK from the source code.

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Sign-off time, bestie: this page is from LAPACK Version 3.12.0 and the source file is SRC/dlarf1l.f(3). The footer date slot isn't shown on this page, so no invented dates here — just cute footer facts. 💖✨