各位高手：该段代码由于需要将4个判断条件都执行才能进行赋值计算，所以执行效率偏低。
如何提高能提高执行效率。
                  for（循环）
                  {
                          if(p[0][im2]<-9990 ||
                             p[1][im2]<-9990 ||
                             p[2][im2]<-9990 ||
                             p[3][im2]<-9990)
                            ptt[im2] = -9990.0f;
                          else
                            ptt[im2]= ff[0]*p[0][im2]
                              + ff[1]*p[1][im2]
                              + ff[2]*p[2][im2]
                              + ff[3]*p[3][im2];
                   }

我做了如下改进：
                                                 if(p[0][im2]<-9990)ptt[im2] = -9990.0f;
                                             else
                                             {
                                                if(p[3][im2]<-9990)ptt[im2] = -9990.0f;
                                                else
                                                {
                                                   if(p[2][im2]<-9990)ptt[im2] = -9990.0f;
                                                   else
                                                   {
                                                      if(p[1][im2]<-9990)ptt[im2] = -9990.0f;
                                                      else ptt[im2]= ff[0]*p[0][im2]
                                                          + ff[1]*p[1][im2]
                                                          + ff[2]*p[2][im2]
                                                          + ff[3]*p[3][im2];
                                                   }
                                                }
                                             }
和
                         if(p[0][im2]>-9990)
                           if(p[3][im2]>-9990)
                              if(p[2][im2]>-9990)
                                if(p[1][im2]>-9990)
                                     ptt[im2]= ff[0]*p[0][im2]
                                                             + ff[1]*p[1][im2]
                                                             + ff[2]*p[2][im2]
                                                             + ff[3]*p[3][im2];
                                  else ptt[im2] = -9990.0f;
                               else ptt[im2] = -9990.0f;
                           else ptt[im2] = -9990.0f;
                         else ptt[im2] = -9990.0f;
发现效果都不理想，请问有没有更好的替代代码？