* Fix a bitch of a bug where 1<I (and all other relationals) returned true.

[ginac.git] / ginac / relational.cpp

diff --git a/ginac/relational.cpp b/ginac/relational.cpp
index 0bc6c70f21c08c810243caaa8f6a96edb6558b49..f657f8100d96ef67a5d1200bc3c4cdb04baf85db 100644 (file)
--- a/ginac/relational.cpp
+++ b/ginac/relational.cpp
@@ -242,30 +242,31 @@ ex relational::rhs(void) const
 // non-virtual functions in this class
 //////////
 
+/** Cast the relational into a boolean, mainly for evaluation within an 
+ *  if-statement.  Note that (a<b) == false does not imply (a>=b) == true in
+ *  the general symbolic case.  A false result means the comparison is either
+ *  false or undecidable (except of course for !=, where true means either
+ *  unequal or undecidable). */
 relational::operator bool() const
 {
-       // please note that (a<b) == false does not imply (a>=b) == true
-       // a false result means the comparison is either false or undecidable
-       // (except for !=, where true means unequal or undecidable)
-       ex df = lh-rh;
+       const ex df = lh-rh;
        if (!is_ex_exactly_of_type(df,numeric))
                // cannot decide on non-numerical results
                return o==not_equal ? true : false;
        
-       int cmpval = ex_to<numeric>(df).compare(_num0());
        switch (o) {
        case equal:
-               return cmpval==0;
+               return ex_to<numeric>(df).is_zero();
        case not_equal:
-               return cmpval!=0;
+               return !ex_to<numeric>(df).is_zero();
        case less:
-               return cmpval<0;
+               return ex_to<numeric>(df)<_num0();
        case less_or_equal:
-               return cmpval<=0;
+               return ex_to<numeric>(df)<=_num0();
        case greater:
-               return cmpval>0;
+               return ex_to<numeric>(df)>_num0();
        case greater_or_equal:
-               return cmpval>=0;
+               return ex_to<numeric>(df)>=_num0();
        default:
                throw(std::logic_error("invalid relational operator"));
        }