LAPACK  3.10.0
LAPACK: Linear Algebra PACKage

◆ srot()

subroutine srot ( integer  N,
real, dimension(*)  SX,
integer  INCX,
real, dimension(*)  SY,
integer  INCY,
real  C,
real  S 
)

SROT

Purpose:
    applies a plane rotation.
Parameters
[in]N
          N is INTEGER
         number of elements in input vector(s)
[in,out]SX
          SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
[in]INCX
          INCX is INTEGER
         storage spacing between elements of SX
[in,out]SY
          SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCY ) )
[in]INCY
          INCY is INTEGER
         storage spacing between elements of SY
[in]C
          C is REAL
[in]S
          S is REAL
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
     jack dongarra, linpack, 3/11/78.
     modified 12/3/93, array(1) declarations changed to array(*)

Definition at line 91 of file srot.f.

92 *
93 * -- Reference BLAS level1 routine --
94 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
95 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
96 *
97 * .. Scalar Arguments ..
98  REAL C,S
99  INTEGER INCX,INCY,N
100 * ..
101 * .. Array Arguments ..
102  REAL SX(*),SY(*)
103 * ..
104 *
105 * =====================================================================
106 *
107 * .. Local Scalars ..
108  REAL STEMP
109  INTEGER I,IX,IY
110 * ..
111  IF (n.LE.0) RETURN
112  IF (incx.EQ.1 .AND. incy.EQ.1) THEN
113 *
114 * code for both increments equal to 1
115 *
116  DO i = 1,n
117  stemp = c*sx(i) + s*sy(i)
118  sy(i) = c*sy(i) - s*sx(i)
119  sx(i) = stemp
120  END DO
121  ELSE
122 *
123 * code for unequal increments or equal increments not equal
124 * to 1
125 *
126  ix = 1
127  iy = 1
128  IF (incx.LT.0) ix = (-n+1)*incx + 1
129  IF (incy.LT.0) iy = (-n+1)*incy + 1
130  DO i = 1,n
131  stemp = c*sx(ix) + s*sy(iy)
132  sy(iy) = c*sy(iy) - s*sx(ix)
133  sx(ix) = stemp
134  ix = ix + incx
135  iy = iy + incy
136  END DO
137  END IF
138  RETURN
139 *
140 * End of SROT
141 *
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