Developer Reference

  • 098
  • 03/30/2020
  • Public Content
Contents

?rotg

Computes the parameters for a Givens rotation.

Syntax

call srotg
(
a
,
b
,
c
,
s
)
call drotg
(
a
,
b
,
c
,
s
)
call crotg
(
a
,
b
,
c
,
s
)
call zrotg
(
a
,
b
,
c
,
s
)
call rotg
(
a
,
b
,
c
,
s
)
Include Files
  • mkl.fi
    ,
    blas.f90
Description
Given the Cartesian coordinates
(
a
,
b
)
of a point,
these
routines return the parameters
c
,
s
,
r
, and
z
associated with the Givens rotation. The parameters
c
and
s
define a unitary matrix such that:
Equation
The parameter
z
is defined such that if |
a
| > |
b
|,
z
is
s
; otherwise if
c
is not 0
z
is 1/
c
; otherwise
z
is 1.
See a more accurate LAPACK version
?lartg
.
Input Parameters
a
REAL
for
srotg
DOUBLE PRECISION
for
drotg
COMPLEX
for
crotg
DOUBLE COMPLEX
for
zrotg
Provides the
x
-coordinate of the point
p
.
b
REAL
for
srotg
DOUBLE PRECISION
for
drotg
COMPLEX
for
crotg
DOUBLE COMPLEX
for
zrotg
Provides the
y
-coordinate of the point
p
.
Output Parameters
a
Contains
the parameter
r
associated with the Givens rotation.
b
Contains
the parameter
z
associated with the Givens rotation.
c
REAL
for
srotg
DOUBLE PRECISION
for
drotg
REAL
for
crotg
DOUBLE PRECISION
for
zrotg
Contains
the parameter
c
associated with the Givens rotation.
s
REAL
for
srotg
DOUBLE PRECISION
for
drotg
COMPLEX
for
crotg
DOUBLE COMPLEX
for
zrotg
Contains
the parameter
s
associated with the Givens rotation.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804