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

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.