Visible to Intel only — GUID: GUID-10E5D95E-5EB2-4EB8-AE10-A6992E85F483
Visible to Intel only — GUID: GUID-10E5D95E-5EB2-4EB8-AE10-A6992E85F483
?larfp
Generates a real or complex elementary reflector.
Syntax
call slarfp(n, alpha, x, incx, tau)
call dlarfp(n, alpha, x, incx, tau)
call clarfp(n, alpha, x, incx, tau)
call zlarfp(n, alpha, x, incx, tau)
Include Files
- mkl.fi
Description
The ?larfp routines generate a real or complex elementary reflector H of order n, such that
H * (alpha) = (beta), ( x ) ( 0 )
and H'*H =I for real flavors, conjg(H)'*H =I for complex flavors.
Here
alpha and beta are scalars, beta is real and non-negative,
x is (n-1)-element vector.
H is represented in the form
H = I - tau*( 1 )* (1 v'), ( v )
where tau is scalar, and v is (n-1)-element vector .
For real flavors if the elements of x are all zero, then tau = 0 and H is taken to be the unit matrix. Otherwise 1 ≤tau≤ 2.
For complex flavors if the elements of x are all zero and alpha is real, then tau = 0 and H is taken to be the unit matrix. Otherwise 1 ≤ real(tau) ≤ 2, and abs (tau-1≤ 1.
Input Parameters
- n
-
INTEGER. Specifies the order of the elementary reflector.
- alpha
-
REAL for slarfp
DOUBLE PRECISION for dlarfp
COMPLEX for clarfp
DOUBLE COMPLEX for zlarfp
Specifies the scalar alpha.
- x
-
REAL for slarfp
DOUBLE PRECISION for dlarfp
COMPLEX for clarfp
DOUBLE COMPLEX for zlarfp
Array, DIMENSION at least (1 + (n - 1)*abs(incx)). It contains the vector x.
- incx
-
INTEGER. Specifies the increment for the elements of x.
The value of incx must not be zero.
Output Parameters
- alpha
-
Overwritten by the value beta.
- y
-
Overwritten by the vector v.
- tau
-
REAL for slarfp
DOUBLE PRECISION for dlarfp
COMPLEX for clarfp
DOUBLE COMPLEX for zlarfp
Contains the scalar tau.