Developer Reference

Contents

?lartgs

Generates a plane rotation designed to introduce a bulge in implicit QR iteration for the bidiagonal SVD problem.

Syntax

lapack_int
LAPACKE_slartgs
(
float
x
,
float
y
,
float
sigma
,
float
*
cs
,
float
*
sn
);
lapack_int
LAPACKE_dlartgs
(
double
x
,
double
y
,
double
sigma
,
double
*
cs
,
double
*
sn
);
Include Files
  • mkl.h
Description
The routine generates a plane rotation designed to introduce a bulge in Golub-Reinsch-style implicit QR iteration for the bidiagonal SVD problem.
x
and
y
are the top-row entries, and
sigma
is the shift. The computed
cs
and
sn
define a plane rotation that satisfies the following:
Equation
with
r
nonnegative.
If
x
2
-
sigma
and
x
*
y
are 0, the rotation is by
π
/2
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.
x
,
y
The (1,1) and (1,2) entries of an upper bidiagonal matrix, respectively.
sigma
Shift
Output Parameters
cs
The cosine of the rotation.
sn
The sine of the rotation.
Return Values
If
info
= 0
, the execution is successful.
If
info
= - 1
,
x
is NaN.
If
info
= - 2
,
y
is NaN.
If
info
= - 3
,
sigma
is NaN.

Product and Performance Information

1

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