.TH "SRC/slartg.f90" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/slartg.f90
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBslartg\fP (f, g, c, s, r)"
.br
.RI "\fBSLARTG\fP generates a plane rotation with real cosine and real sine\&. "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine slartg (real(wp) f, real(wp) g, real(wp) c, real(wp) s, real(wp) r)"

.PP
\fBSLARTG\fP generates a plane rotation with real cosine and real sine\&. 
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
!>
!> SLARTG generates a plane rotation so that
!>
!>    [  C  S  ]  \&.  [ F ]  =  [ R ]
!>    [ -S  C  ]     [ G ]     [ 0 ]
!>
!> where C**2 + S**2 = 1\&.
!>
!> The mathematical formulas used for C and S are
!>    R = sign(F) * sqrt(F**2 + G**2)
!>    C = F / R
!>    S = G / R
!> Hence C >= 0\&. The algorithm used to compute these quantities
!> incorporates scaling to avoid overflow or underflow in computing the
!> square root of the sum of squares\&.
!>
!> This version is discontinuous in R at F = 0 but it returns the same
!> C and S as CLARTG for complex inputs (F,0) and (G,0)\&.
!>
!> This is a more accurate version of the BLAS1 routine SROTG,
!> with the following other differences:
!>    F and G are unchanged on return\&.
!>    If G=0, then C=1 and S=0\&.
!>    If F=0 and (G \&.ne\&. 0), then C=0 and S=sign(1,G) without doing any
!>       floating point operations (saves work in SBDSQR when
!>       there are zeros on the diagonal)\&.
!>
!> Below, wp=>sp stands for single precision from LA_CONSTANTS module\&.
!> 
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIF\fP 
.PP
.nf
!>          F is REAL(wp)
!>          The first component of vector to be rotated\&.
!> 
.fi
.PP
.br
\fIG\fP 
.PP
.nf
!>          G is REAL(wp)
!>          The second component of vector to be rotated\&.
!> 
.fi
.PP
.br
\fIC\fP 
.PP
.nf
!>          C is REAL(wp)
!>          The cosine of the rotation\&.
!> 
.fi
.PP
.br
\fIS\fP 
.PP
.nf
!>          S is REAL(wp)
!>          The sine of the rotation\&.
!> 
.fi
.PP
.br
\fIR\fP 
.PP
.nf
!>          R is REAL(wp)
!>          The nonzero component of the rotated vector\&.
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Edward Anderson, Lockheed Martin 
.RE
.PP
\fBDate\fP
.RS 4
July 2016 
.RE
.PP
\fBContributors:\fP
.RS 4
Weslley Pereira, University of Colorado Denver, USA 
.RE
.PP
\fBFurther Details:\fP
.RS 4

.PP
.nf
!>
!>  Anderson E\&. (2017)
!>  Algorithm 978: Safe Scaling in the Level 1 BLAS
!>  ACM Trans Math Softw 44:1--28
!>  https://doi\&.org/10\&.1145/3061665
!>
!> 
.fi
.PP
 
.RE
.PP

.PP
Definition at line \fB110\fP of file \fBslartg\&.f90\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.