c++里的指数、对数等

c++有个现成的头文件，#include 加入它之后就可以用exp()来表示自然对数e的指数，log（）用来求对数，还有

_STD_BEGIN
using _CSTD acosf; using _CSTD asinf;
using _CSTD atanf; using _CSTD atan2f; using _CSTD ceilf;
using _CSTD cosf; using _CSTD coshf; using _CSTD expf;
using _CSTD fabsf; using _CSTD floorf; using _CSTD fmodf;
using _CSTD frexpf; using _CSTD ldexpf; using _CSTD logf;
using _CSTD log10f; using _CSTD modff; using _CSTD powf;
using _CSTD sinf; using _CSTD sinhf; using _CSTD sqrtf;
using _CSTD tanf; using _CSTD tanhf;


using _CSTD acosl; using _CSTD asinl;
using _CSTD atanl; using _CSTD atan2l; using _CSTD ceill;
using _CSTD cosl; using _CSTD coshl; using _CSTD expl;
using _CSTD fabsl; using _CSTD floorl; using _CSTD fmodl;
using _CSTD frexpl; using _CSTD ldexpl; using _CSTD logl;
using _CSTD log10l; using _CSTD modfl; using _CSTD powl;
using _CSTD sinl; using _CSTD sinhl; using _CSTD sqrtl;
using _CSTD tanl; using _CSTD tanhl;