/* what I get after just typing */
{NUMBER}  {
sscanf(yytext, "%lf", &yylval);
return NUMBER;
}

    /* what I get after doing `=yap` */
{NUMBER}  {
    sscanf(yytext,"%lf", &yylval);
    return NUMBER;
          }

    /* what I want */
{NUMBER}  {
               sscanf(yytext,"%lf", &yylval);
               return NUMBER;
          }