Ncalc Options

The CoreCLR-NCalc provides various options that can modify the way the evaluation is performed.

Case Sensitive Evaluation

The code evaluation is case-sensitive by default. Let's say you want to evaluate the following different expressions.

public static void Example1()
{
    List<string> expressions = new List<string>()
    {
        "ABS(-3.2);",
        "acos(-0.5);",
        "Floor(4.23);",
        "IeeeRemainder(9, 8);",
        "log10(1000);",
    };

    foreach (var expr in expressions)
    {
        try
        {
            Expression evaluator = new Expression(expr, EvaluateOptions.IgnoreCase);
            var result = evaluator.Evaluate();
            Console.WriteLine($"{expr}\t {result}");
        }
        catch (EvaluationException e)
        {
            Console.WriteLine(e.Message);
        }
    }
}

When you execute the above code you will get the exceptions for those expressions which are not in the camel case.

Function not found ABS. Try Abs instead.
Function not found acos. Try Acos instead.
Floor(4.23);     4
Function not found IeeeRemainder. Try IEEERemainder instead.
Function not found log10. Try Log10 instead.

Now to make the code evaluation case insensitive, we need to pass the EvaluateOptions.IgnoreCase argument when creating the Expression instance.

public static void Example2()
{
    List<string> expressions = new List<string>()
    {
        "ABS(-3.2);",
        "acos(-0.5);",
        "Floor(4.23);",
        "IeeeRemainder(9, 8);",
        "log10(1000);",
    };

    foreach (var expr in expressions)
    {
        try
        {
            Expression evaluator = new Expression(expr, EvaluateOptions.IgnoreCase);
            var result = evaluator.Evaluate();
            Console.WriteLine($"{expr}\t {result}");
        }
        catch (EvaluationException e)
        {
            Console.WriteLine(e.Message);
        }
    }
}

Let's execute the above code and you will see the following output.

ABS(-3.2);       3.2
acos(-0.5);      2.0943951023931957
Floor(4.23);     4
IeeeRemainder(9, 8);     1
log10(1000);     3

Multi-valued Parameters

By default, a single value is used as a parameter. Now, if you want to use an array or of IEnumerable type, we need to pass the EvaluateOptions.IterateParameters argument when creating the Expression instance.

public static void Example5()
{
    Expression expression = new Expression("x ^ c + y", EvaluateOptions.IterateParameters);

    expression.Parameters["x"] = new int[] { 1, 3, 5, 7, 9 };
    expression.Parameters["y"] = new int[] { 0, 2, 4, 6, 8 };
    expression.Parameters["c"] = 3;

    var results = (IList)expression.Evaluate();

    foreach (var result in results)
    {
        Console.WriteLine(result);
    }
}

Let's execute the above code, and you will see the following output.

ABS(-3.2);       3.2
acos(-0.5);      2.0943951023931957
Floor(4.23);     4
IeeeRemainder(9, 8);     1
log10(1000);     3