LOG_PI_OVER_2      76 missing/erf.c      if (x >= 0) return   p_gamma(0.5, x * x, LOG_PI_OVER_2);
LOG_PI_OVER_2      77 missing/erf.c      else        return - p_gamma(0.5, x * x, LOG_PI_OVER_2);
LOG_PI_OVER_2      86 missing/erf.c      if (x >= 0) return  q_gamma(0.5, x * x, LOG_PI_OVER_2);
LOG_PI_OVER_2      87 missing/erf.c      else        return  1 + p_gamma(0.5, x * x, LOG_PI_OVER_2);