+
+/** ctor from C-style string. It also accepts complex numbers in GiNaC
+ * notation like "2+5*I". */
+numeric::numeric(const char *s) : basic(TINFO_numeric)
+{
+ debugmsg("numeric constructor from string",LOGLEVEL_CONSTRUCT);
+ value = new ::cl_N(0);
+ // parse complex numbers (functional but not completely safe, unfortunately
+ // std::string does not understand regexpese):
+ // ss should represent a simple sum like 2+5*I
+ std::string ss(s);
+ // make it safe by adding explicit sign
+ if (ss.at(0) != '+' && ss.at(0) != '-' && ss.at(0) != '#')
+ ss = '+' + ss;
+ std::string::size_type delim;
+ do {
+ // chop ss into terms from left to right
+ std::string term;
+ bool imaginary = false;
+ delim = ss.find_first_of(std::string("+-"),1);
+ // Do we have an exponent marker like "31.415E-1"? If so, hop on!
+ if (delim != std::string::npos &&
+ ss.at(delim-1) == 'E')
+ delim = ss.find_first_of(std::string("+-"),delim+1);
+ term = ss.substr(0,delim);
+ if (delim != std::string::npos)
+ ss = ss.substr(delim);
+ // is the term imaginary?
+ if (term.find("I") != std::string::npos) {
+ // erase 'I':
+ term = term.replace(term.find("I"),1,"");
+ // erase '*':
+ if (term.find("*") != std::string::npos)
+ term = term.replace(term.find("*"),1,"");
+ // correct for trivial +/-I without explicit factor on I:
+ if (term.size() == 1)
+ term += "1";
+ imaginary = true;
+ }
+ const char *cs = term.c_str();
+ // CLN's short types are not useful within the GiNaC framework, hence
+ // we go straight to the construction of a long float. Simply using
+ // cl_N(s) would require us to use add a CLN exponent mark, otherwise
+ // we would not be save from over-/underflows.
+ if (strchr(cs, '.'))
+ if (imaginary)
+ *value = *value + ::complex(cl_I(0),::cl_LF(cs));
+ else
+ *value = *value + ::cl_LF(cs);
+ else
+ if (imaginary)
+ *value = *value + ::complex(cl_I(0),::cl_R(cs));
+ else
+ *value = *value + ::cl_R(cs);
+ } while(delim != std::string::npos);