LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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## ◆ slar2v()

 subroutine slar2v ( integer N, real, dimension( * ) X, real, dimension( * ) Y, real, dimension( * ) Z, integer INCX, real, dimension( * ) C, real, dimension( * ) S, integer INCC )

SLAR2V applies a vector of plane rotations with real cosines and real sines from both sides to a sequence of 2-by-2 symmetric/Hermitian matrices.

Purpose:
``` SLAR2V 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. For i = 1,2,...,n

( x(i)  z(i) ) := (  c(i)  s(i) ) ( x(i)  z(i) ) ( c(i) -s(i) )
( z(i)  y(i) )    ( -s(i)  c(i) ) ( z(i)  y(i) ) ( s(i)  c(i) )```
Parameters
 [in] N ``` N is INTEGER The number of plane rotations to be applied.``` [in,out] X ``` X is REAL array, dimension (1+(N-1)*INCX) The vector x.``` [in,out] Y ``` Y is REAL array, dimension (1+(N-1)*INCX) The vector y.``` [in,out] Z ``` Z is REAL array, dimension (1+(N-1)*INCX) The vector z.``` [in] INCX ``` INCX is INTEGER The increment between elements of X, Y and Z. INCX > 0.``` [in] C ``` C is REAL array, dimension (1+(N-1)*INCC) The cosines of the plane rotations.``` [in] S ``` S is REAL array, dimension (1+(N-1)*INCC) The sines of the plane rotations.``` [in] INCC ``` INCC is INTEGER The increment between elements of C and S. INCC > 0.```

Definition at line 109 of file slar2v.f.

110*
111* -- LAPACK auxiliary routine --
112* -- LAPACK is a software package provided by Univ. of Tennessee, --
113* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
114*
115* .. Scalar Arguments ..
116 INTEGER INCC, INCX, N
117* ..
118* .. Array Arguments ..
119 REAL C( * ), S( * ), X( * ), Y( * ), Z( * )
120* ..
121*
122* =====================================================================
123*
124* .. Local Scalars ..
125 INTEGER I, IC, IX
126 REAL CI, SI, T1, T2, T3, T4, T5, T6, XI, YI, ZI
127* ..
128* .. Executable Statements ..
129*
130 ix = 1
131 ic = 1
132 DO 10 i = 1, n
133 xi = x( ix )
134 yi = y( ix )
135 zi = z( ix )
136 ci = c( ic )
137 si = s( ic )
138 t1 = si*zi
139 t2 = ci*zi
140 t3 = t2 - si*xi
141 t4 = t2 + si*yi
142 t5 = ci*xi + t1
143 t6 = ci*yi - t1
144 x( ix ) = ci*t5 + si*t4
145 y( ix ) = ci*t6 - si*t3
146 z( ix ) = ci*t4 - si*t5
147 ix = ix + incx
148 ic = ic + incc
149 10 CONTINUE
150*
151* End of SLAR2V
152*
153 RETURN
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