Contents
droti - Apply an indexed Givens rotation.
SUBROUTINE DROTI(NZ, X, INDX, Y, C, S)
INTEGER NZ
INTEGER INDX(*)
DOUBLE PRECISION C, S
DOUBLE PRECISION X(*), Y(*)
SUBROUTINE DROTI_64(NZ, X, INDX, Y, C, S)
INTEGER*8 NZ
INTEGER*8 INDX(*)
DOUBLE PRECISION C, S
DOUBLE PRECISION X(*), Y(*)
F95 INTERFACE
SUBROUTINE ROTI([NZ], X, INDX, Y, C, S)
INTEGER :: NZ
INTEGER, DIMENSION(:) :: INDX
REAL(8) :: C, S
REAL(8), DIMENSION(:) :: X, Y
SUBROUTINE ROTI_64([NZ], X, INDX, Y, C, S)
INTEGER(8) :: NZ
INTEGER(8), DIMENSION(:) :: INDX
REAL(8) :: C, S
REAL(8), DIMENSION(:) :: X, Y
DROTI - Applies a Givens rotation to a sparse vector x
stored in compressed form and another vector y in full
storage form
do i = 1, n
temp = -s * x(i) + c * y(indx(i))
x(i) = c * x(i) + s * y(indx(i))
y(indx(i)) = temp
enddo
NZ (input) - INTEGER
Number of elements in the compressed form.
Unchanged on exit.
X (input)
Vector containing the values of the compressed form.
INDX (input) - INTEGER
Vector containing the indices of the compressed
form. It is assumed that the elements in INDX are
distinct and greater than zero. Unchanged on exit.
Y (input/output)
Vector on input which contains the vector Y in full
storage form. On exit, only the elements
corresponding to the indices in INDX have been
modified.
C (input)
Scalar defining the Givens rotation
S (input)
Scalar defining the Givens rotation