added fix helper

src/helper.rs

@@ -7,6 +7,22 @@ use evalexpr::{
 use crate::util;
 
 //	Mathematics
+pub fn fix(arg: &Value) -> Result<Value, EvalexprError> {
+	let args = arg.as_tuple()?;
+
+	let count = args.len();
+	if count != 2 {
+		return Err(EvalexprError::WrongFunctionArgumentAmount { expected: 2, actual: count });
+	}
+
+	let float = args[0].as_float()?;
+	let figures = args[1].as_int()?;
+
+	let operand: f64 = i64::pow(10, figures as u32) as f64;
+	let output = f64::round(float * operand) / operand;
+	return Ok(output.into());
+}
+
 pub fn logarithm(arg: &Value) -> Result<Value, EvalexprError> {
 	let arguments: Vec<Value>;
 	let count: usize;

src/main.rs

@@ -36,6 +36,7 @@ fn main() {
 		"√2"	=>	global::ROOT_TWO,
 
 		//	math functions
+		"fix"	=>	Function::new(|arg| helper::fix(arg)),
 		"log"	=>	Function::new(|arg| helper::logarithm(arg)),
 		"sqrt"	=>	Function::new(|arg| helper::square_root(arg)),