studio中进行对数运算的问题

#include <math.h>
int main(void)
{
    LOG_I("application starting...");
    ah_beep_ok();
    ah_led_blink(0, 500);
    double a = 123.456;
    LOG_I("log(%f)=%f", a ,log(a));
    return RT_EOK;
}