Implement rem for P

This one doesn't need shift.

1 files changed, 27 insertions, 7 deletions

diff --git a/src/poly.rs b/src/poly.rs
index 3f298cb..f6ee63c 100644
--- a/src/poly.rs
+++ b/src/poly.rs
@@ -4,7 +4,7 @@ use crate::number::Number;
 use iter::Iter;
 use std::cmp;
 use std::cmp::Ordering;
-use std::ops::{Add, Sub, Mul};
+use std::ops::{Add, Sub, Mul, Rem};
 use std::iter::{Sum, Zip, Take};
 
 #[derive(PartialEq, Debug)]
@@ -65,6 +65,26 @@ impl Mul for &P {
     }
 }
 
+impl Rem for &P {
+    type Output = P;
+
+    fn rem(self, other: Self) -> P {
+        let ad = self.degree();
+        let bd = other.degree();
+        let an = self.0[ad];
+        let bn = other.0[bd];
+        match ad.cmp(&bd) {
+            Ordering::Equal => self - &(other * &P(vec![an / bn])),
+            Ordering::Greater => {
+                let mut qv = vec![0.0; ad];
+                qv[ad - bd] = an / bn;
+                self - &(other * &P(qv))
+            },
+            Ordering::Less => P(vec![0.0])
+        }
+    }
+}
+
 //****************************REFACTORING************************************
 
 pub type Poly = Vec<Number>;
@@ -213,16 +233,16 @@ mod tests {
 
     #[test]
     fn rem_equal() {
-        let a = vec![6.0, 7.0, 1.0];
-        let b = vec![-6.0, -5.0, 1.0];
-        assert_eq!(rem(&a, &b), vec![12.0, 12.0, 0.0]);
+        let a = P(vec![6.0, 7.0, 1.0]);
+        let b = P(vec![-6.0, -5.0, 1.0]);
+        assert_eq!(&a % &b, P(vec![12.0, 12.0, 0.0]));
     }
 
     #[test]
     fn rem_greater() {
-        let a = vec![-6.0, -5.0, 1.0];
-        let b = vec![12.0, 12.0, 0.0];
-        assert_eq!(rem(&a, &b), vec![-6.0, -6.0, 0.0]);
+        let a = P(vec![-6.0, -5.0, 1.0]);
+        let b = P(vec![12.0, 12.0, 0.0]);
+        assert_eq!(&a % &b, P(vec![-6.0, -6.0, 0.0]));
     }
 
     #[test]