relational::operator relational::safe_bool() const
{
const ex df = lh-rh;
- if (!is_exactly_a<numeric>(df))
- // cannot decide on non-numerical results
- return o==not_equal ? make_safe_bool(true) : make_safe_bool(false);
-
- switch (o) {
- case equal:
- return make_safe_bool(ex_to<numeric>(df).is_zero());
- case not_equal:
- return make_safe_bool(!ex_to<numeric>(df).is_zero());
- case less:
- return make_safe_bool(ex_to<numeric>(df)<(*_num0_p));
- case less_or_equal:
- return make_safe_bool(ex_to<numeric>(df)<=(*_num0_p));
- case greater:
- return make_safe_bool(ex_to<numeric>(df)>(*_num0_p));
- case greater_or_equal:
- return make_safe_bool(ex_to<numeric>(df)>=(*_num0_p));
- default:
- throw(std::logic_error("invalid relational operator"));
+ // We treat numeric and symbolic expression differently
+ if (is_exactly_a<numeric>(df)) {
+ switch (o) {
+ case equal:
+ return make_safe_bool(ex_to<numeric>(df).is_zero());
+ case not_equal:
+ return make_safe_bool(!ex_to<numeric>(df).is_zero());
+ case less:
+ return make_safe_bool(ex_to<numeric>(df)<(*_num0_p));
+ case less_or_equal:
+ return make_safe_bool(ex_to<numeric>(df)<=(*_num0_p));
+ case greater:
+ return make_safe_bool(ex_to<numeric>(df)>(*_num0_p));
+ case greater_or_equal:
+ return make_safe_bool(ex_to<numeric>(df)>=(*_num0_p));
+ default:
+ throw(std::logic_error("invalid relational operator"));
+ }
+ } else {
+ // The conversion for symbolic expressions is based on the info flags
+ switch (o) {
+ case equal:
+ return make_safe_bool(df.is_zero());
+ case not_equal:
+ return make_safe_bool(! df.is_zero());
+ case less:
+ return make_safe_bool(df.info(info_flags::negative));
+ case less_or_equal:
+ return make_safe_bool((-df).info(info_flags::nonnegative));
+ case greater:
+ return make_safe_bool(df.info(info_flags::positive));
+ case greater_or_equal:
+ return make_safe_bool(df.info(info_flags::nonnegative));
+ default:
+ throw(std::logic_error("invalid relational operator"));
+ }
}
}