建議用 dataex (先 ssc install dataex 并见说明) 将原始 Stata 资料中具有”代表性”的一部分资料列出，以供有意回答者实验之用，并能提供具体操作指令。

请问是提供这个吗？

list   if rate=float(6.7744)




Programming function

    float(x)
       Domain:       -1e+38 to 1e+38
       Range:        -1e+38 to 1e+38
       Description:  returns the value of x rounded to float precision.

                     Although you may store your numeric variables as byte, int, long,
                     float, or double, Stata converts all numbers to double before
                     performing any calculations.  Consequently, difficulties can arise in
                     comparing numbers that have no finite binary representations.

                     For example, if the variable x is stored as a float and contains the
                     value 1.1 (a repeating "decimal" in binary), the expression x==1.1
                     will evaluate to false because the literal 1.1 is the double
                     representation of 1.1, which is different from the float
                     representation stored in x.  (They differ by 2.384 x 10^(-8).) The
                     expression x==float(1.1) will evaluate to true because the float()
                     function converts the literal 1.1 to its float representation before
                     it is compared with x. (See [U] 13.11 Precision and problems therein
                     for more information.)

明白了！谢谢大神！