dlartg (l) - Linux Manuals
dlartg: generate a plane rotation so that [ CS SN ]
Command to display dlartg manual in Linux: $ man l dlartg
NAME
DLARTG - generate a plane rotation so that [ CS SN ]
SYNOPSIS
- SUBROUTINE DLARTG(
-
F, G, CS, SN, R )
-
DOUBLE
PRECISION CS, F, G, R, SN
PURPOSE
DLARTG generate a plane rotation so that
[
-SN CS ] [ G ] [ 0 ]
This is a slower, more accurate version of the BLAS1 routine DROTG,
with the following other differences:
F and G are unchanged on return.
If G=0, then CS=1 and SN=0.
If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any
floating point operations (saves work in DBDSQR when
there are zeros on the diagonal).
If F exceeds G in magnitude, CS will be positive.
ARGUMENTS
- F (input) DOUBLE PRECISION
-
The first component of vector to be rotated.
- G (input) DOUBLE PRECISION
-
The second component of vector to be rotated.
- CS (output) DOUBLE PRECISION
-
The cosine of the rotation.
- SN (output) DOUBLE PRECISION
-
The sine of the rotation.
- R (output) DOUBLE PRECISION
-
The nonzero component of the rotated vector.
This version has a few statements commented out for thread safety
(machine parameters are computed on each entry). 10 feb 03, SJH.
Pages related to dlartg
- dlartg (3)
- dlartv (l) - applies a vector of real plane rotations to elements of the real vectors x and y
- dlar1v (l) - computes the (scaled) r-th column of the inverse of the sumbmatrix in rows B1 through BN of the tridiagonal matrix L D L^T - sigma I
- dlar2v (l) - applies a vector of real plane rotations from both sides to a sequence of 2-by-2 real symmetric matrices, defined by the elements of the vectors x, y and z
- dlarf (l) - applies a real elementary reflector H to a real m by n matrix C, from either the left or the right
- dlarfb (l) - applies a real block reflector H or its transpose Haq to a real m by n matrix C, from either the left or the right
- dlarfg (l) - generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
- dlarfp (l) - generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
- dlarft (l) - forms the triangular factor T of a real block reflector H of order n, which is defined as a product of k elementary reflectors
- dlarfx (l) - applies a real elementary reflector H to a real m by n matrix C, from either the left or the right