Added pow function.

I'll try adding some unchecked and in place variants soon.

src/linalg/mod.rs

@@ -19,6 +19,7 @@ pub mod householder;
 mod inverse;
 mod lu;
 mod permutation_sequence;
+mod pow;
 mod qr;
 mod schur;
 mod solve;
@@ -41,6 +42,7 @@ pub use self::full_piv_lu::*;
 pub use self::hessenberg::*;
 pub use self::lu::*;
 pub use self::permutation_sequence::*;
+pub use self::pow::*;
 pub use self::qr::*;
 pub use self::schur::*;
 pub use self::svd::*;

src/linalg/pow.rs

@@ -0,0 +1,52 @@
+//! This module provides the matrix exponential (pow) function to square matrices.
+
+use std::ops::DivAssign;
+
+use crate::{allocator::Allocator, DefaultAllocator, DimMin, DimMinimum, MatrixN};
+use num::PrimInt;
+use simba::scalar::ComplexField;
+
+impl<N: ComplexField, D> MatrixN<N, D>
+where
+    D: DimMin<D, Output = D>,
+    DefaultAllocator: Allocator<N, D, D>
+        + Allocator<(usize, usize), DimMinimum<D, D>>
+        + Allocator<N, D>
+        + Allocator<N::RealField, D>
+        + Allocator<N::RealField, D, D>,
+{
+    /// Raises a matrix to an integer power using exponentiation by squares.
+    /// Returns `None` only when the matrix is non-invertible and raised to a
+    /// negative power.
+    pub fn pow<T: PrimInt + DivAssign>(&self, mut e: T) -> Option<Self> {
+        let zero = T::zero();
+
+        if e == zero {
+            let mut i = self.clone();
+            i.fill_with_identity();
+            return Some(i);
+        }
+
+        let mut acc;
+        if e < zero {
+            acc = self.clone().try_inverse()?;
+        } else {
+            acc = self.clone();
+        }
+
+        let one = T::one();
+        let two = T::from(2u8).unwrap();
+        let mut multiplier = acc.clone();
+
+        while e != zero {
+            if e % two == one {
+                acc *= &multiplier;
+            }
+
+            e /= two;
+            multiplier *= multiplier.clone();
+        }
+
+        Some(acc)
+    }
+}