sqrt开平方 返回值为double,我想把他转成float ,怎么转?

Question

我这样转出错了
result = (float)(num_elect/sqrt(num_elect + num_apex_paddy));

Answer 1

先
String a=String.valueOf(num_elect/sqrt(num_elect + num_apex_paddy));
然后
float b=Float.parseFloat(a);

Answer 2

复杂点的
Double(d).floatValue() ------------------------------------------------------
           我们还年轻牛奶会有的奶牛也会有的 
             可天天在 csdn 混这些会有吗 ??

Answer 3

我的程序是这样的:
  public float Calculate_power_factor(float number_electron,float number_apex_paddy){
      float result;
      double num_elect;
      double num_apex_paddy;
      double res;      num_elect = (double)number_electron;
      num_apex_paddy = (double)number_apex_paddy;      res = num_elect/sqrt(num_elect * num_elect + num_apex_paddy * num_apex_paddy);
 
      result = (float)res;

      return result;  
  }出错如下:
C:\bea\user_projects\119\Alert\.wlnotdelete\DefaultWebApp_DefaultWebApp_4795646\jsp_servlet\__e_input_otherunits_electrodata.java:143: cannot resolve symbol
probably occurred due to an error in /E_input_Otherunits_electrodata.jsp line 74:
res = num_elect/sqrt(num_elect * num_elect + num_apex_paddy * num_apex_paddy);

Answer 4

我的程序是这样的:
  public float Calculate_power_factor(float number_electron,float number_apex_paddy){
      float result;
      double num_elect;
      double num_apex_paddy;
      double res;      num_elect = (double)number_electron;
      num_apex_paddy = (double)number_apex_paddy;      res = num_elect/sqrt(num_elect * num_elect + num_apex_paddy * num_apex_paddy);
 
      result = (float)res;

      return result;  
  }出错如下:
C:\bea\user_projects\119\Alert\.wlnotdelete\DefaultWebApp_DefaultWebApp_4795646\jsp_servlet\__e_input_otherunits_electrodata.java:143: cannot resolve symbol
probably occurred due to an error in /E_input_Otherunits_electrodata.jsp line 74:
res = num_elect/sqrt(num_elect * num_elect + num_apex_paddy * num_apex_paddy);