Developer Reference

Contents

?lartgp

Generates a plane rotation.

Syntax

lapack_int
LAPACKE_slartgp
(
float
f
,
float
g
,
float
*
cs
,
float
*
sn
,
float
*
r
);
lapack_int
LAPACKE_dlartgp
(
double
f
,
double
g
,
double
*
cs
,
double
*
sn
,
double
*
r
);
Include Files
  • mkl.h
Description
The routine generates a plane rotation so that
Equation
where
cs
2
+
sn
2
= 1
This is a slower, more accurate version of the BLAS Level 1 routine
?rotg
, except for the following differences:
  • f
    and
    g
    are unchanged on return.
  • If
    g
    =0, then
    cs
    =(+/-)1 and
    sn
    =0.
  • If
    f
    =0 and
    g
    0, then
    cs
    =0 and
    sn
    =(+/-)1.
The sign is chosen so that
r
0.
Input Parameters
A
<datatype>
placeholder, if present, is used for the C interface data types in the C interface section above. See C Interface Conventions for the C interface principal conventions and type definitions.
f
,
g
The first and second component of the vector to be rotated.
Output Parameters
cs
The cosine of the rotation.
sn
The sine of the rotation.
r
The nonzero component of the rotated vector.
Return Values
If
info
= 0
, the execution is successful.
If
info
=-1
,
f
is NaN.
If
info
= -2
,
g
is NaN.

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