e

E

src/user/bin/calc/functions.rs

@@ -2,6 +2,8 @@ use alloc::format;
 use alloc::string::String;
 use crate::println;
 
+const PI: f64 = 3.14159265358979323846264338327950288419716939937510;
+
 pub fn run_func(func: String, x: f64) -> Result<f64, String> {
     match func.as_str() {
         "sqrt" => sqrt(x),
@@ -36,14 +38,51 @@ fn factorial(x: f64) -> Result<f64, String> {
     Ok((1..=x).fold(1, |a, b| a * b) as f64)
 }
 
-fn sin(x: f64) -> Result<f64, String> {
-    Ok(libm::sin(x))
+fn cos(mut x: f64) -> Result<f64, String> {
+    while x > PI {
+        x -= PI;
+    }
+    
+    let res = 1.0 - trig_term(x, 2) + trig_term(x, 4) - trig_term(x, 6) + trig_term(x, 8) - trig_term(x, 10);
+    if res >= -1.0 && res <= 1.0 {
+        Ok(res)
+    } else {
+        panic!("something is very wrong with the cos function : {}", res);
+    }
 }
 
-fn cos(x: f64) -> Result<f64, String> {
-    Ok(libm::cos(x))
+fn sin(mut x: f64) -> Result<f64, String> {
+    while x > PI {
+        x -= PI;
+    }
+
+    
+    let res = x - trig_term(x, 3) + trig_term(x, 5) - trig_term(x, 7) + trig_term(x, 9) - trig_term(x, 11);
+    if res >= -1.0 && res <= 1.0 {
+        Ok(res) 
+    } else {
+        panic!("something is very wrong with the sin function: {}", res);
+    }
 }
 
 fn tan(x: f64) -> Result<f64, String> {
     Ok(libm::tan(x))
+}
+
+pub fn exp(x: f64, y: f64) -> f64 {
+    let mut res = 1.0;
+    for _ in 0..(y as usize) {
+        res *= x
+    }
+    res
+}
+
+fn trig_term(x: f64, y: usize) -> f64 {
+    let mut ex = 1.0;
+    for _ in 0..y {
+        ex *= x;
+    }
+    let fact = (1..=y).fold(1, |a, b| a*b);
+
+    ex as f64 / fact as f64
 }