erfc函数在c语言中用什么头文件

P= 0.5*erfc(0.5*sqrt(snr));我要在C++Builder里编，头文件该用什么呢?我用#include ，提示说没有定义erfc。

#include

float用printf("%f"来表示，double用printf("%ld"来表示。 把英文帮助找出来了，自己看看吧。 函数原型： #include double erfc(double x); float erfcf(float x); long double erfcl(long double x); link with -lm. 编译时需要链接 -lm description 说明 the erfc() function returns the complementary error function of x, that is, 1.0 - erf(x). return value 返回值 on success, these functions return the complementary error function of x, a value in the range [0,2]. if x is a nan, a nan is returned. if x is +0 or -0, 1 is returned. if x is positive infinity, +0 is returned. if x is negative infinity, +2 is returned. if the function result underflows and produces an unrepresentable value, the return value is 0.0. if the function result underflows but produces a representable (i.e., subnormal) value, that value is returned, and a range error occurs.