Functions
Built-in Functions
The framework includes a set of already implemented functions.
| Name | Description | Usage | Result |
|---|---|---|---|
| Abs | Returns the absolute value of a specified number. | Abs(-1) | 1d |
| Acos | Returns the angle whose cosine is the specified number. | Acos(1) | 0d |
| Asin | Returns the angle whose sine is the specified number. | Asin(0) | 0d |
| Atan | Returns the angle whose tangent is the specified number. | Atan(0) | 0d |
| Ceiling | Returns the smallest integer greater than or equal to the specified number. | Ceiling(1.5) | 2d |
| Cos | Returns the cosine of the specified angle. | Cos(0) | 1d |
| Exp | Returns e raised to the specified power. | Exp(0) | 1d |
| Floor | Returns the largest integer less than or equal to the specified number. | Floor(1.5) | 1d |
| IEEERemainder | Returns the remainder resulting from the division of a specified number by another specified number. | IEEERemainder(3, 2) | -1d |
| Ln | Returns the natural logarithm of a specified number. | Ln(1) | 0d |
| Log | Returns the logarithm of a specified number. | Log(1, 10) | 0d |
| Log10 | Returns the base 10 logarithm of a specified number. | Log10(1) | 0d |
| Max | Returns the larger of two specified numbers. | Max(1, 2) | 2 |
| Min | Returns the smaller of two numbers. | Min(1, 2) | 1 |
| Pow | Returns a specified number raised to the specified power. | Pow(3, 2) | 9d |
| Round | Rounds a value to the nearest integer or specified number of decimal places. The mid number behaviour can be changed by using ExpressionOptions.RoundAwayFromZero during construction of the Expression object. | Round(3.222, 2) | 3.22d |
| Sign | Returns a value indicating the sign of a number. | Sign(-10) | -1 |
| Sin | Returns the sine of the specified angle. | Sin(0) | 0d |
| Sqrt | Returns the square root of a specified number. | Sqrt(4) | 2d |
| Tan | Returns the tangent of the specified angle. | Tan(0) | 0d |
| Truncate | Calculates the integral part of a number. | Truncate(1.7) | 1 |
It also includes other general purpose ones.
| Name | Description | Usage | Result |
|---|---|---|---|
| in | Returns whether an element is in a set of values. | in(1 + 1, 1, 2, 3) | true |
| if | Returns a value based on a condition. | if(3 % 2 = 1, 'value is true', 'value is false') | 'value is true' |
| ifs | Returns a value based on evaluating a number of conditions, returning a default if none are true. | ifs(foo > 50, "bar", foo > 75, "baz", "quux") | if foo is between 50 and 75 "bar", foo greater than 75 "baz", otherwise "quux" |
You can use comma (,) or semicolon (;) as argument separator.
If DecimalAsDefault is used all functions will cast the arguments to decimal.
You can get the functions from the <xref:NCalc.ExpressionBuiltInFuctions> class.
Custom Functions
Custom functions are created using the ExpressionFunction delegate. The parameters are Expression instances that can be lazy evaluated.
expression.Functions["SecretOperation"] = (args, context) => {
return (int)args[0].Evaluate() + (int)args[1].Evaluate();
};
Using Event Handlers
You can also use event handlers to handle functions.
expression.EvaluateFunction += delegate(string name, FunctionArgs args)
{
if (name == "SecretOperation")
args.Result = (int)args.Parameters[0].Evaluate() + (int)args.Parameters[1].Evaluate();
};
Case Sensitivity
See case_sensitivity for more info.