그래서 OpenCL에서 복잡한 숫자를 처리하는 함수 집합이 필요 했으므로이 집합을 구현했습니다. 특히 나는 합과 빼기 (사소한, 표준 벡터 연산으로 수행 할 수 있음), 곱하기, 나누기, 복소수 모듈러스, 인수 (또는 각도) 및 제곱근 가져 오기가 필요했습니다.
관련 위키 피 디아 기사 :
http://en.wikipedia.org/wiki/Complex_number#Absolute_value_and_argument
http://en.wikipedia.org/wiki/Square_root#Principal_square_root_of_a_complex_number
이 대부분 사소한, 그러나 사람이 시간을 절약 할 수있는 희망 그래서, 시간이 좀 걸릴 않습니다, 여기 간다 :
//2 component vector to hold the real and imaginary parts of a complex number:
typedef float2 cfloat;
#define I ((cfloat)(0.0, 1.0))
/*
* Return Real (Imaginary) component of complex number:
*/
inline float real(cfloat a){
return a.x;
}
inline float imag(cfloat a){
return a.y;
}
/*
* Get the modulus of a complex number (its length):
*/
inline float cmod(cfloat a){
return (sqrt(a.x*a.x + a.y*a.y));
}
/*
* Get the argument of a complex number (its angle):
* http://en.wikipedia.org/wiki/Complex_number#Absolute_value_and_argument
*/
inline float carg(cfloat a){
if(a.x > 0){
return atan(a.y/a.x);
}else if(a.x < 0 && a.y >= 0){
return atan(a.y/a.x) + M_PI;
}else if(a.x < 0 && a.y < 0){
return atan(a.y/a.x) - M_PI;
}else if(a.x == 0 && a.y > 0){
return M_PI/2;
}else if(a.x == 0 && a.y < 0){
return -M_PI/2;
}else{
return 0;
}
}
/*
* Multiply two complex numbers:
*
* a = (aReal + I*aImag)
* b = (bReal + I*bImag)
* a * b = (aReal + I*aImag) * (bReal + I*bImag)
* = aReal*bReal +I*aReal*bImag +I*aImag*bReal +I^2*aImag*bImag
* = (aReal*bReal - aImag*bImag) + I*(aReal*bImag + aImag*bReal)
*/
inline cfloat cmult(cfloat a, cfloat b){
return (cfloat)(a.x*b.x - a.y*b.y, a.x*b.y + a.y*b.x);
}
/*
* Divide two complex numbers:
*
* aReal + I*aImag (aReal + I*aImag) * (bReal - I*bImag)
* ----------------- = ---------------------------------------
* bReal + I*bImag (bReal + I*bImag) * (bReal - I*bImag)
*
* aReal*bReal - I*aReal*bImag + I*aImag*bReal - I^2*aImag*bImag
* = ---------------------------------------------------------------
* bReal^2 - I*bReal*bImag + I*bImag*bReal -I^2*bImag^2
*
* aReal*bReal + aImag*bImag aImag*bReal - Real*bImag
* = ---------------------------- + I* --------------------------
* bReal^2 + bImag^2 bReal^2 + bImag^2
*
*/
inline cfloat cdiv(cfloat a, cfloat b){
return (cfloat)((a.x*b.x + a.y*b.y)/(b.x*b.x + b.y*b.y), (a.y*b.x - a.x*b.y)/(b.x*b.x + b.y*b.y));
}
/*
* Square root of complex number.
* Although a complex number has two square roots, numerically we will
* only determine one of them -the principal square root, see wikipedia
* for more info:
* http://en.wikipedia.org/wiki/Square_root#Principal_square_root_of_a_complex_number
*/
inline cfloat csqrt(cfloat a){
return (cfloat)(sqrt(cmod(a)) * cos(carg(a)/2), sqrt(cmod(a)) * sin(carg(a)/2));
}
여기에 조 그것을하는 방법을 llustrates : http://developer.amd.com/resources/documentation-articles/articles-whitepapers/opencl-optimization-case-study-fast-fourier-transform-part-1/ – ChrisF