updates to rational and piecewise

.dockerignore

@@ -0,0 +1,40 @@
+# Rust build artifacts
+target/
+debug/
+release/
+
+# Cargo metadata / local caches
+.cargo/
+
+# Git
+.git/
+.gitignore
+
+# IDE / editor
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# Environment / secrets
+.env
+.env.*
+
+# Logs
+*.log
+
+# Docker / compose overrides (optional)
+docker-compose.override.yml
+
+# Test / temp outputs
+*.tmp
+*.bak
+
+# Generated artifacts
+*.png
+*.svg
+*.pdf

src/functions.rs

@@ -2,3 +2,7 @@ pub mod polynomial;
 pub mod rational;
 
 pub mod radical;
+
+mod exponential;
+mod logarithmic;
+pub mod piecewise;

src/functions/exponential.rs

@@ -0,0 +1 @@
+

src/functions/logarithmic.rs

@@ -0,0 +1 @@
+

src/functions/piecewise.rs

@@ -0,0 +1,15 @@
+use crate::core::traits::Function;
+
+pub struct Piecewise {
+    functions: Vec<Box<dyn Function>>,
+}
+
+impl Piecewise {
+    pub fn count(&self) -> usize {
+        self.functions.len()
+    }
+
+    pub fn functions(&self) -> &[Box<dyn Function>] {
+        &self.functions
+    }
+}

src/functions/polynomial.rs

@@ -1,4 +1,4 @@
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq)]
 pub struct Polynomial {
     /// Coefficients in descending degree order.
     /// Example: x^2 - 4x + 3 => vec![1.0, -4.0, 3.0]
@@ -64,11 +64,6 @@ impl Polynomial {
         Polynomial::new(result)
     }
 
-    pub fn evaluate(&self, x: f64) -> f64 {
-        // Horner's method
-        self.coefficients.iter().fold(0.0, |acc, &c| acc * x + c)
-    }
-
     pub fn derivative(&self) -> Self {
         let degree = self.degree();
 
@@ -94,6 +89,11 @@ impl Polynomial {
         self.evaluate(0.0)
     }
 
+    pub fn evaluate(&self, x: f64) -> f64 {
+        // Horner's method
+        self.coefficients.iter().fold(0.0, |acc, &c| acc * x + c)
+    }
+
     pub fn leading_coefficient(&self) -> f64 {
         self.coefficients[0]
     }

src/functions/rational.rs

@@ -4,8 +4,8 @@ use crate::functions::polynomial::Polynomial;
 pub struct Rational {
     /// Coefficients in descending degree order.
     /// Example: x^2 - 4x + 3 => vec![1.0, -4.0, 3.0]
-    pub numerator: Polynomial,
-    pub denominator: Polynomial,
+    numerator: Polynomial,
+    denominator: Polynomial,
 }
 
 impl Rational {
@@ -15,4 +15,33 @@ impl Rational {
             denominator,
         }
     }
+
+    pub fn asymptote(&self) -> Polynomial {
+        let numerator = &self.numerator;
+        let denominator = &self.denominator;
+        if numerator.degree() == denominator.degree() {
+            let ratio = numerator.leading_coefficient() / denominator.leading_coefficient();
+            Polynomial::new(vec![ratio])
+        } else if numerator.degree() > denominator.degree() {
+            Polynomial::new(vec![])
+        } else {
+            Polynomial::new(vec![0.0])
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn expect_horizontal_asymptote_zero() {
+        let numerator = Polynomial::new(vec![1.0, 1.0]);
+        let denominator = Polynomial::new(vec![1.0, 1.0, 1.0]);
+        let rational = Rational::new(numerator, denominator);
+        let asymptote: Polynomial = rational.asymptote();
+
+        let horizontal_expected: Polynomial = Polynomial::new(vec![0.0]);
+        assert_eq!(asymptote, horizontal_expected);
+    }
 }