blob: f5586ea0939f061d908c973b3c9c6a91dfe95c1c [file] [log] [blame]
 /* * There are multiple formulas for calculating arccosine of x: * 1) acos(x) = (1/2*pi) + i * ln(i*x + sqrt(1-x^2)) (notice the 'i'...) * 2) acos(x) = pi/2 + asin(-x) (asin isn't implemented yet) * 3) acos(x) = pi/2 - asin(x) (ditto) * 4) acos(x) = 2*atan2(sqrt(1-x), sqrt(1+x)) * 5) acos(x) = pi/2 - atan2(x, ( sqrt(1-x^2) ) ) * * Options 1-3 are not currently usable, #5 generates more concise radeonsi * bitcode and assembly than #4 (134 vs 132 instructions on radeonsi), but * precision of #4 may be better. */ // TODO: Enable half precision when atan2 is implemented #if __CLC_FPSIZE > 16 #if __CLC_FPSIZE == 64 #define __CLC_CONST(x) x #elif __CLC_FPSIZE == 32 #define __CLC_CONST(x) x ## f #elif __CLC_FPSIZE == 16 #define __CLC_CONST(x) x ## h #endif _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE acos(__CLC_GENTYPE x) { return ( (__CLC_GENTYPE) __CLC_CONST(2.0) * atan2( sqrt((__CLC_GENTYPE) __CLC_CONST(1.0) - x), sqrt((__CLC_GENTYPE) __CLC_CONST(1.0) + x) ) ); } #undef __CLC_CONST #endif