Developer Reference

  • 2020
  • 07/15/2020
  • Public Content
Contents

Atan2

Computes four-quadrant inverse tangent of elements of two vectors.

Syntax

IppStatus ippsAtan2_32f_A11 (const Ipp32f*
pSrc1
, const Ipp32f*
pSrc2
, Ipp32f*
pDst
, Ipp32s
len
);
IppStatus ippsAtan2_32f_A21 (const Ipp32f*
pSrc1
, const Ipp32f*
pSrc2
, Ipp32f*
pDst
, Ipp32s
len
);
IppStatus ippsAtan2_32f_A24 (const Ipp32f*
pSrc1
, const Ipp32f*
pSrc2
, Ipp32f*
pDst
, Ipp32s
len
);
IppStatus ippsAtan2_64f_A26 (const Ipp64f*
pSrc1
, const Ipp64f*
pSrc2
, Ipp64f*
pDst
, Ipp32s
len
);
IppStatus ippsAtan2_64f_A50 (const Ipp64f*
pSrc1
, const Ipp64f*
pSrc2
, Ipp64f*
pDst
, Ipp32s
len
);
IppStatus ippsAtan2_64f_A53 (const Ipp64f*
pSrc1
, const Ipp64f*
pSrc2
, Ipp64f*
pDst
, Ipp32s
len
);
Include Files
ippvm.h
Domain Dependencies
Headers:
ippcore.h
Libraries:
ippcore.lib
Parameters
pSrc1
Pointer to the first source vector.
pSrc2
Pointer to the second source vector.
pDst
Pointer to the destination vector.
len
Number of elements in the vectors.
Description
This function computes the angle between the
X
axis and the line from the origin to the point
(X,Y)
, for each element of
pSrc1
as a
Y
(the ordinate) and corresponding element of
pSrc2
as an
X
(the abscissa), and stores the result in the corresponding element of
pDst
. The result angle varies from - π to + π.
For single precision data:
function flavor
ippsAtan2_32f_A11
guarantees 11 correctly rounded bits of significand, or at least 3 exact decimal digits;
function flavor
ippsAtan2_32f_A21
guarantees 21 correctly rounded bits of significand, or 4 ulps, or about 6 exact decimal digits;
function flavor
ippsAtan2_32f_A24
guarantees 24 correctly rounded bits of significand, including the implied bit, with the maximum guaranteed error within 1 ulp.
For double precision data:
function flavor
ippsAtan2_64f_A26
guarantees 26 correctly rounded bits of significand, or 6.7E+7 ulps, or approximately 8 exact decimal digits;
function flavor
ippsAtan2_64f_A50
guarantees 50 correctly rounded bits of significand, or 4 ulps, or approximately 15 exact decimal digits;
function flavor
ippsAtan2_64f_A53
guarantees 53 correctly rounded bits of significand, including the implied bit, with the maximum guaranteed error within 1 ulp.
The computation is performed as follows:
pDst
[n] = atan2(
pSrc1
[n],
pSrc2
[n])
,
0 ≤ n <
len
.
Return Values
ippStsNoErr
Indicates no error.
ippStsNullPtrErr
Indicates an error when
pSrc1
,
pSrc2
or
pDst
pointer is
NULL
.
ippStsSizeErr
Indicates an error when
len
is less than or equal to 0.

Example

The example below shows how to use the function
ippsAtan2
.
IppStatus ippsAtan2_32f_A21_sample(void)
{
const Ipp32f x1[4] = {1.492, 1.700, 1.147, 1.142};
const Ipp32f x2[4] = {1.064, 1.505, 1.950, 1.905};
Ipp32f y[4];
IppStatus st = ippsAtan2_32f_A21( x1, x2, y, 4 );
printf(" ippsAtan2_32f_A21:\n");
printf(" x1 = %.3f %.3f %.3f %.3f \n", x1[0], x1[1], x1[2], x1[3]);
printf(" x2 = %.3f %.3f %.3f %.3f \n", x2[0], x2[1], x2[2], x2[3]);
printf(" y = %.3f %.3f %.3f %.3f \n", y[0], y[1], y[2], y[3]);
return st;
}
Output results:
ippsAtan2_32f_A21:
x1 = 1.492 1.700 1.147 1.142
x2 = 1.064 1.505 1.950 1.905
y = 0.951 0.846 0.532 0.540

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