问一个很小的%if问题

%macro a;
%let a=2;%let b=-2;%let c=-2.38050453744706;
%if &a>0 %then %put &a;
%if &b>0 %then %put &b;
%if &c>0 %then %put &c;
%mend;
%a;

如上程序，请问，为什么 c 没有被put出来？谢谢

********补充**************8；

我自己有个解决方案，钻了个空子：
%macro a;
%let a=2;%let b=-2;%let c=-2.38050453744706;
%if &a>0 %then %put &a;
%if &b>0 %then %put &b;
%if %substr(&c,1,2)>0 %then %put &c;   *这样就不报错了;
%mend;
%a;

SAS  implicitly uses %eval function to do a comparison in SAS macro language. This is correct when all elements are inters. Otherwise one needs to use %syaevalf if any of them is a floating number.


%macro a;
%let a=1;%let b=-2;%let c=2.38050453744706;
%if %sysevalf(&a>0) %then %put &a;
%if %sysevalf(&b>0) %then %put &b;
%if %sysevalf(&c>0) %then %put &c;
%mend;
%a;

C＝-2.38050453744706 ，小于0，为什么会PUT 出来？

%macro a;
%let a=2;%let b=-2;%let c=-2.38050453744706;
%if &a>0 %then %put &a;
%if &b>0 %then %put &b;
%if %sysevalf(&c,boolean)>0 %then %put &c;   /*Use %SYSEVALF(expression<, conversion-type>)*/
%mend;
%a;