SROT/DROT/CROT/CSROT/ZROT/ZDROT

Apply Givens rotation

Name SROT/DROT/CROT/CSROT/ZROT/ZDROT

Apply Givens rotation

Purpose Given a real scalar c, a real or complex scalar, s and real or complex vectors x

and y of length n, these subprograms apply the Givens rotation

 

xi

←

 

c

s

⋅

xi

for i = 1, …, n

 

yi

–s

c

yi

where s

is the complex conjugate of s; s = s if s is real. The vectors can be

stored in one-dimensional arrays or in either rows or columns of two-dimensional arrays. The indexing through the arrays can be either forward or backward.

Usually, c and s have been determined by the companion subprogram SROTG, DROTG, CROTG, or ZROTG.

Usage

VECLIB:

 

 

INTEGER*4

n, incx, incy

 

REAL*4

x(lenx), y(leny), c, s

 

CALL SROT(n, x, incx, y, incy, c, s)

 

INTEGER*4

n, incx, incy

 

REAL*8

x(lenx), y(leny), c, s

 

CALL DROT(n, x, incx, y, incy, c, s)

 

INTEGER*4

n, incx, incy

 

REAL*4

c

 

COMPLEX*8

x(lenx), y(leny), s

 

CALL CROT(n, x, incx, y, incy, c, s)

 

INTEGER*4

n, incx, incy

 

REAL*4

c, s

 

COMPLEX*8

x(lenx), y(leny)

CALL CSROT(n, x, incx, y, incy, c, s)

INTEGER*4

n, incx, incy

REAL*8

c

COMPLEX*16

x(lenx), y(leny), s

CALL ZROT(n, x, incx, y, incy, c, s)

114HP MLIB User’s Guide