1 // Simple example file for the function parser
2 // ===========================================
3 /* Note that the library has to be compiled with
4 FP_SUPPORT_FLOAT_TYPE, FP_SUPPORT_LONG_DOUBLE_TYPE and
5 FP_SUPPORT_LONG_INT_TYPE
6 preprocessor macros defined for this example to work.
7
8 Try with these input values with the different floating point parser
9 types to see the difference in accuracy:
10
11 f(x) = x + 1.234567890123456789
12 min x: 0
13 max x: 2
14 step: 1
15 */
16
17 #include "../fparser.hh"
18
19 #include <iostream>
20 #include <iomanip>
21 #include <string>
22
23 template<typename Parser>
runExample(const char * valueTypeName)24 void runExample(const char* valueTypeName)
25 {
26 typedef typename Parser::value_type Value_t;
27
28 std::cout << "Using " << valueTypeName << " parser." << std::endl;
29
30 Parser fparser;
31 std::string function;
32 Value_t minx, maxx, step;
33
34 fparser.AddConstant("pi", Value_t(3.1415926535897932));
35
36 std::cin.ignore();
37 while(true)
38 {
39 std::cout << "f(x) = ";
40 std::getline(std::cin, function);
41 if(std::cin.fail()) return;
42
43 int res = fparser.Parse(function, "x");
44 if(res < 0) break;
45
46 std::cout << std::string(res+7, ' ') << "^\n"
47 << fparser.ErrorMsg() << "\n\n";
48 }
49
50 std::cout << "min x: ";
51 std::cin >> minx;
52 std::cout << "max x: ";
53 std::cin >> maxx;
54 std::cout << "step: ";
55 std::cin >> step;
56 if(std::cin.fail()) return;
57
58 Value_t vals[] = { 0 };
59 for(vals[0] = minx; vals[0] <= maxx; vals[0] += step)
60 {
61 std::cout << std::setprecision(20);
62 std::cout << "f(" << vals[0] << ") = " << fparser.Eval(vals)
63 << std::endl;
64 }
65 }
66
main()67 int main()
68 {
69 int choice = 0;
70 do
71 {
72 std::cout << "1 = double, 2 = float, 3 = long double, 4 = long int: ";
73 std::cin >> choice;
74 } while(choice < 1 || choice > 4);
75
76 switch(choice)
77 {
78 case 1: runExample<FunctionParser>("double"); break;
79 case 2: runExample<FunctionParser_f>("float"); break;
80 case 3: runExample<FunctionParser_ld>("long double"); break;
81 case 4: runExample<FunctionParser_li>("long int"); break;
82 }
83
84 return 0;
85 }
86