Check perlfaq4, under Data:Misc, the second faq is how can you determine whether a string is an integer or float. As you said that you are new, I copied a piece from the answer, and pasted it here, hope it helps.

It basically said two things:

• You can do it by yourself, use regexp, and the regexp's you needed are listed below.
• If you want call some module, there is a CPAN module.

(As you said the entity you want to check is returned from some math function, maybe I can assume the return is a number. If that is true, you can just check whether int($num) == $num.)

Assuming that you don't care about IEEE notations like ``NaN'' or ``In
+finity'', you probably just want to use a regular expression.

   if (/\D/)            { print "has nondigits\n" }
   if (/^\d+$/)         { print "is a whole number\n" }
   if (/^-?\d+$/)       { print "is an integer\n" }
   if (/^[+-]?\d+$/)    { print "is a +/- integer\n" }
   if (/^-?\d+\.?\d*$/) { print "is a real number\n" }
   if (/^-?(?:\d+(?:\.\d*)?|\.\d+)$/) { print "is a decimal number\n" 
+}
   if (/^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/)
                        { print "a C float\n" }You can also use the Da
+ta::Types module on the CPAN, which exports functions that validate d
+ata types using these and other
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