message: removed unnecessary Hessian type
diff: @@ -22,7 +22,7 @@ use std::default::Default;
  /// Conjugate Gradient struct
  #[derive(ArgminSolver)]
  -pub struct ConjugateGradient<'a, T, H>
  +pub struct ConjugateGradient<'a, T>
  where
  T: Clone
  + Default
  @@ -32,7 +32,6 @@ where
  + ArgminDot<T, f64>
  + ArgminScaledAdd<T, f64>
  + ArgminScaledSub<T, f64>,
  - H: Clone + Default,
  {
  /// b
  b: T,
  @@ -47,10 +46,10 @@ where
  /// beta
  beta: f64,
  /// base
  - base: ArgminBase<'a, T, T, H>,
  + base: ArgminBase<'a, T, T, ()>,
  }
  -impl<'a, T, H> ConjugateGradient<'a, T, H>
  +impl<'a, T> ConjugateGradient<'a, T>
  where
  T: Clone
  + Default
  @@ -60,7 +59,6 @@ where
  + ArgminDot<T, f64>
  + ArgminScaledAdd<T, f64>
  + ArgminScaledSub<T, f64>,
  - H: Clone + Default,
  {
  /// Constructor
  ///
  @@ -69,7 +67,7 @@ where
  /// `cost_function`: cost function
  /// `init_param`: Initial parameter vector
  pub fn new(
  - operator: Box<ArgminOperator<Parameters = T, OperatorOutput = T, Hessian = H>>,
  + operator: Box<ArgminOperator<Parameters = T, OperatorOutput = T, Hessian = ()>>,
  b: T,
  init_param: T,
  ) -> Result<Self, Error> {
  @@ -85,7 +83,7 @@ where
  }
  }
  -impl<'a, T, H> ArgminNextIter for ConjugateGradient<'a, T, H>
  +impl<'a, T> ArgminNextIter for ConjugateGradient<'a, T>
  where
  T: Clone
  + Default
  @@ -95,11 +93,10 @@ where
  + ArgminDot<T, f64>
  + ArgminScaledAdd<T, f64>
  + ArgminScaledSub<T, f64>,
  - H: Clone + Default,
  {
  type Parameters = T;
  type OperatorOutput = T;
  - type Hessian = H;
  + type Hessian = ();
  fn init(&mut self) -> Result<(), Error> {
  let init_param = self.cur_param();
  