.

.

src/user/bin/calc/functions.rs

@@ -3,11 +3,13 @@ use alloc::string::String;
 use crate::println;
 
 pub fn run_func(func: String, x: f64) -> Result<f64, String> {
-    println!("function being run: {}({})", func, x);
-
     match func.as_str() {
         "sqrt" => sqrt(x),
         "ln" => ln(x),
+        "fact" => factorial(x),
+        "sin" => sin(x),
+        "cos" => cos(x),
+        "tan" => tan(x),
         _ => Err(String::from(format!("unrecognised function name: {}", func))),
     }
 }
@@ -24,4 +26,24 @@ fn ln(x: f64) -> Result<f64, String> {
         return Err(String::from("Cannot take the natural log of a negative number"));
     }
     Ok(libm::log(x))
+}
+
+fn factorial(x: f64) -> Result<f64, String> {
+    if x < 0.0 {
+        return Err(String::from("Cannot take the factorial of a negative number"));
+    }
+    let x = x as u64;
+    Ok((1..=x).fold(1, |a, b| a * b) as f64)
+}
+
+fn sin(x: f64) -> Result<f64, String> {
+    Ok(libm::sin(x))
+}
+
+fn cos(x: f64) -> Result<f64, String> {
+    Ok(libm::cos(x))
+}
+
+fn tan(x: f64) -> Result<f64, String> {
+    Ok(libm::tan(x))
 }