fix all tests

src/approximation/linear_approximation.rs

@@ -96,7 +96,7 @@ impl<D: DerivatorMultiVariable> LinearApproximator<D>
 {
     pub fn from_derivator(derivator: D) -> Self
     {
-        return LinearApproximator {derivator: derivator}
+        return LinearApproximator {derivator}
     }
 
     /// For an n-dimensional approximation, the equation is linearized as:
@@ -108,16 +108,17 @@ impl<D: DerivatorMultiVariable> LinearApproximator<D>
     ///
     ///example function is x + y^2 + z^3, which we want to linearize. First define the function:
     ///```
-    ///use multicalc::approximation::linear_approximation;
+    ///use multicalc::approximation::linear_approximation::*;
+    ///use multicalc::numerical_derivative::finite_difference::MultiVariableSolver;
     /// 
     ///let function_to_approximate = | args: &[f64; 3] | -> f64
     ///{ 
     ///    return args[0] + args[1].powf(2.0) + args[2].powf(3.0);
     ///};
     ///
     ///let point = [1.0, 2.0, 3.0]; //the point we want to linearize around
-    ///
-    ///let result = linear_approximation::get(&function_to_approximate, &point);
+    ///let approximator = LinearApproximator::<MultiVariableSolver>::default();
+    ///let result = approximator.get(&function_to_approximate, &point).unwrap();
     ///
     ///assert!(f64::abs(function_to_approximate(&point) - result.get_prediction_value(&point)) < 1e-9);
     /// ```

src/approximation/quadratic_approximation.rs

@@ -106,7 +106,7 @@ impl<D: DerivatorMultiVariable> QuadraticApproximator<D>
 {
     pub fn from_derivator(derivator: D) -> Self
     {
-        return QuadraticApproximator {derivator: derivator};
+        return QuadraticApproximator {derivator};
     }
 
     /// For an n-dimensional approximation, the equation is approximated as I + L + Q, where:
@@ -120,16 +120,18 @@ impl<D: DerivatorMultiVariable> QuadraticApproximator<D>
     /// 
     ///example function is e^(x/2) + sin(y) + 2.0*z, which we want to approximate. First define the function:
     ///```
-    ///use multicalc::approximation::quadratic_approximation;
+    ///use multicalc::approximation::quadratic_approximation::*;
+    ///use multicalc::numerical_derivative::finite_difference::MultiVariableSolver;
     /// 
     ///let function_to_approximate = | args: &[f64; 3] | -> f64
     ///{ 
     ///    return f64::exp(args[0]/2.0) + f64::sin(args[1]) + 2.0*args[2];
     ///};
     ///
     ///let point = [0.0, 1.57, 10.0]; //the point we want to approximate around
-    ///
-    ///let result = quadratic_approximation::get(&function_to_approximate, &point);
+    /// 
+    ///let approximator = QuadraticApproximator::<MultiVariableSolver>::default();
+    ///let result = approximator.get(&function_to_approximate, &point).unwrap();
     ///
     ///assert!(f64::abs(function_to_approximate(&point) - result.get_prediction_value(&point)) < 1e-9);
     /// ```

src/numerical_derivative/derivator.rs

@@ -1,5 +1,7 @@
 use num_complex::ComplexFloat;
 
+
+///Base trait for single variable numerical differentiation
 pub trait DerivatorSingleVariable: Default + Clone + Copy
 {
     ///generic n-th derivative of a single variable function
@@ -18,6 +20,8 @@ pub trait DerivatorSingleVariable: Default + Clone + Copy
     }
 }
 
+
+///Base trait for multi-variable numerical differentiation
 pub trait DerivatorMultiVariable: Default + Clone + Copy
 {
     ///generic n-th derivative for a multivariable function of a multivariable function