Make small adjustments to code

src/Data/NumIdr/Matrix.idr

@@ -350,7 +350,7 @@ detWithLUP : (Ord a, Abs a, Neg a, Fractional a) =>
             (mat : Matrix' n a) -> DecompLUP mat -> a
 detWithLUP {n} mat lup =
   (if numSwaps lup `mod` 2 == 0 then 1 else -1)
-    * product (diagonal lup.lower) * product (diagonal lup.upper)
+    * product (diagonal lup.lu)
 
 export
 det : (Ord a, Abs a, Neg a, Fractional a) => Matrix' n a -> a

src/Data/NumIdr/Multiply.idr

@@ -56,7 +56,7 @@ namespace Monoid
 ||| Raise a multiplicative value (e.g. a matrix or a transformation) to a natural
 ||| number power.
 public export
-power : MultGroup a => Nat -> a -> a
+power : MultMonoid a => Nat -> a -> a
 power 0 _ = identity
 power 1 x = x
 power (S n@(S _)) x = x *. power n x
@@ -66,5 +66,5 @@ power (S n@(S _)) x = x *. power n x
 |||
 ||| This is the operator form of `power`.
 public export %inline
-(^) : MultGroup a => a -> Nat -> a
+(^) : MultMonoid a => a -> Nat -> a
 a ^ n = power n a