How to Evaluate Custom Mathematical Expressions Efficiently in C Using ExprTk?

Evaluating Custom Mathematical Expressions in C

Evaluating complex mathematical expressions in C can be a challenging task. One popular approach involves embedding Python into C , utilizing its robust expression evaluation capabilities. However, alternative solutions exist that may offer improved performance or simplicity.

One such solution is the ExprTk library. Designed specifically for mathematical expression evaluation, ExprTk provides a comprehensive set of functions and operators, enabling the efficient evaluation of arbitrary expressions.

Implementation Using ExprTk

Consider the following custom expression:

3 + sqrt(5) + pow(3) + log(5)

Using ExprTk, we can derive a simple and straightforward solution:

<code class="cpp">#include <exprtk.hpp>

typedef exprtk::expression<double> expression_t;
typedef exprtk::parser<double>         parser_t;

int main()
{
    std::string expression_string = "3 + sqrt(5) + pow(3,2) + log(5)";

    expression_t expression;
    parser_t parser;

    if (parser.compile(expression_string, expression))
    {
        double result = expression.value();

        printf("Result: %19.15f\n", result);
    }
    else
        printf("Error in expression.\n");

    return 0;
}</code>

Benefits of ExprTk:

• Performance: Optimized for fast evaluation of mathematical expressions.
• Simplicity: Provides a concise and intuitive API for defining and evaluating expressions.
• Extensibility: Supports user-defined functions and operators for custom evaluations.

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