A tiny c++ math library for evaluate and recognize expressions.

Example:

try {
    Parser evaluator;
    char expression[] = "1.0e0 + 2 * 3 - 123^2.0";
    evaluator.evaluate_expression_with_exception(expression);
    evaluator.parse(expression);

    double result = evaluator.get_numeric_answer();

    cout << "Ans: " << result << endl;

} catch(ParsingException ex) {
    cout << "Error: " << ex.get_msg() << ", at " << ex.get_col() << endl;
}

Features:

Operators:

&& ||
== != < > <= >=
+ -
* / %
^
!
Scientific notation

Functions:

- factorial
- log
- acot
- acosh
- sign
- acos
- asech
- atan
- asinh
- atanh
- acoth
- asin
- acsc
- acsch
- asec
- cot
- coth
- csc
- csch
- log10
- log2
- sec
- sech
- sqrt
- tan
- rand_0_to_1
- sin
- cos

Numeric constants:

pi
e
g (gravity)
random (random number)

User defined variables:

char expression[] = "sin(pi + x)";        
p.get_vars().add("x", 1.0);
p.parse(expression);
double result = p.get_numeric_answer();

Recognition:

try {
    char expression[] = "pi^2.0 - sin(cos(tan(3.2e0)";
    p.evaluate_expression_with_exception(expression);
    cout << "Ok ... " << endl;
} catch(ParsingException ex) {
    cout << "Error: " << ex.get_msg() << endl;
}

Evaluation:

try {
    char expression[] = "pi^2.0 - sin(cos(tan(3.2e0)))";
    p.evaluate_expression_with_exception(expression);
    p.parse(expression);
    double r = p.get_numeric_answer();
    cout << "Ok ... " << r << endl;
} catch(ParsingException ex) {
    cout << "Error: " << ex.get_msg() << endl;
}

Arrays:

Parser p;
p.get_arrays().create_array("a");

for(int i = 1; i <= 10; i++) {
    p.get_arrays().add_element_to_array("a", (double)i);
}

try {
    char expression[] = "a[sin(pi) + 2]^3";
    p.parse(expression);
    double r = p.get_numeric_answer();
    cout << "Ok ... " << r << endl;
} catch(ParsingException ex) {
    cout << "Error: " << ex.get_msg() << endl;
}

Tokenization:

try {
    char expression[] = "a[sin(pi) + 2]^3";
    Parser p;
    p.extract_tokens(expression);

    vector<Lexema> tokens = p.get_lexemas_positions();

    for(size_t i = 0; i < tokens.size(); i++) {
        cout << tokens[i] << endl;
    }

} catch(ParsingException ex) {
    cout << "Error: " << ex.get_msg() << endl;
}

Output:

{a, init(0), tipo(OPERADOR)}
{[, init(1), tipo(DELIMITADOR)}
{sin, init(2), tipo(FUNCION)}
{(, init(5), tipo(DELIMITADOR)}
{pi, init(6), tipo(VARIABLE)}
{), init(8), tipo(DELIMITADOR)}
{+, init(10), tipo(DELIMITADOR)}
{2, init(12), tipo(NUMERO)}
{], init(13), tipo(DELIMITADOR)}
{^, init(14), tipo(DELIMITADOR)}
{3, init(15), tipo(NUMERO)}

Function domain checking (trigonometric functions):

try {
    Parser p;
    char expression[] = "1 + asin(1.2)";
    p.evaluate_expression_with_exception(expression);
    p.parse(expression);
} catch(ParsingException ex) {
    cout << "Error: " << ex.get_msg() << endl;
}

Output:

Error: out of domain for function '1.200000'