stm32c语言arctan函数,全定点 快速 ATAN2 反正切函数

仿照TI的IQMATH 定点数学库，自己写了个定点的数学库，方便在ARM7/9,DSP,CORTEX-M3上使用。

使用例子：float  temp6=fix2float(arctan(float2fix(1),float2fix(1)));

int32_t arctan( int32_t y, int32_t x )

{

const int32_t ONEQTR_PI = float2fix(M_PI / 4.0);

const int32_t THRQTR_PI = float2fix(3.0 * M_PI / 4.0);

const int32_t OP1 =float2fix(0.1963f);

const int32_t OP2 =float2fix(0.9817f);

const int32_t LEF =float2fix(1e-10f);

int32_t r, angle;

int32_t  abs_y = abs(y)+LEF;      // kludge to prevent 0/0 condition

if ( x < 0 )

{

r = fixdiv((x + abs_y) , (abs_y - x));

angle = THRQTR_PI;

}

else

{

r = fixdiv((x - abs_y) , (x + abs_y));

angle = ONEQTR_PI;

}

//angle =angle + (0.1963f * r * r - 0.9817f) * r;

angle += fixmulf(  (fixmulf(OP1,fixmulf(r,r))- OP2),   r);

if ( y < 0 )

return( -angle );     // negate if in quad III or IV

else

return( angle );

}