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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_atan2_f32.c
* Description: float32 Arc tangent of y/x
*
* $Date: 22 April 2022
* $Revision: V1.10.0
*
* Target Processor: Cortex-M and Cortex-A cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2022 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "dsp/fast_math_functions.h"
/*
atan for argument between in [0, 1.0]
*/
#define ATANHALFF32 0.463648f
#define PIHALFF32 1.5707963267948966192313f
#define ATAN2_NB_COEFS_F32 10
static const float32_t atan2_coefs_f32[ATAN2_NB_COEFS_F32]={0.0f
,1.0000001638308195518f
,-0.0000228941363602264f
,-0.3328086544578890873f
,-0.004404814619311061f
,0.2162217461808173258f
,-0.0207504842057097504f
,-0.1745263362250363339f
,0.1340557235283553386f
,-0.0323664125927477625f
};
__STATIC_FORCEINLINE float32_t arm_atan_limited_f32(float32_t x)
{
float32_t res=atan2_coefs_f32[ATAN2_NB_COEFS_F32-1];
int i=1;
for(i=1;i<ATAN2_NB_COEFS_F32;i++)
{
res = x*res + atan2_coefs_f32[ATAN2_NB_COEFS_F32-1-i];
}
return(res);
}
__STATIC_FORCEINLINE float32_t arm_atan_f32(float32_t x)
{
int sign=0;
float32_t res=0.0f;
if (x < 0.0f)
{
sign=1;
x=-x;
}
if (x > 1.0f)
{
x = 1.0f / x;
res = PIHALFF32 - arm_atan_limited_f32(x);
}
else
{
res += arm_atan_limited_f32(x);
}
if (sign)
{
res = -res;
}
return(res);
}
/**
@ingroup groupFastMath
*/
/**
@defgroup atan2 ArcTan2
Computing Arc tangent only using the ratio y/x is not enough to determine the angle
since there is an indeterminacy. Opposite quadrants are giving the same ratio.
ArcTan2 is not using y/x to compute the angle but y and x and use the sign of y and x
to determine the quadrant.
*/
/**
@addtogroup atan2
@{
*/
/**
@brief Arc Tangent of y/x using sign of y and x to get right quadrant
@param[in] y y coordinate
@param[in] x x coordinate
@param[out] result Result
@return error status.
@par Compute the Arc tangent of y/x:
The sign of y and x are used to determine the right quadrant
and compute the right angle.
*/
arm_status arm_atan2_f32(float32_t y,float32_t x,float32_t *result)
{
if (x > 0.0f)
{
*result=arm_atan_f32(y/x);
return(ARM_MATH_SUCCESS);
}
if (x < 0.0f)
{
if (y > 0.0f)
{
*result=arm_atan_f32(y/x) + PI;
}
else if (y < 0.0f)
{
*result=arm_atan_f32(y/x) - PI;
}
else
{
if (signbit(y))
{
*result= -PI;
}
else
{
*result= PI;
}
}
return(ARM_MATH_SUCCESS);
}
if (x == 0.0f)
{
if (y > 0.0f)
{
*result=PIHALFF32;
return(ARM_MATH_SUCCESS);
}
if (y < 0.0f)
{
*result=-PIHALFF32;
return(ARM_MATH_SUCCESS);
}
}
return(ARM_MATH_NANINF);
}
/**
@} end of atan2 group
*/
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