Add ROBER preset

Author: Steven-Roberts

toolbox/+otp/+robertson/+presets/Canonical.m

@@ -1,6 +1,11 @@
 classdef Canonical < otp.robertson.RobertsonProblem
-    % The Robertson problem with the classic coefficients $K_1 = 4\times 10^{-2}$, $K_2 = 3\times 10^7$, $K_3 = 10^4$ :cite:p:`Rob67`. This preset is
-    % referred to as "ROBER" in :cite:p:`HW96` (pg 144).
+    % The original configuration :cite:p:`Rob67` with $t \in [0, 40]$, $y_0 = [1, 0, 0]^T$, and parameters
+    %
+    % $$
+    % K_1 &= 4\times 10^{-2}, \\
+    % K_2 &= 3\times 10^7, \\
+    % K_3 &= 10^4.
+    % $$
     methods
         function obj = Canonical
             % Create the Canonical Robertson problem object.
@@ -19,7 +24,7 @@
             params.K3 = 1e4;
 
             y0 = [1; 0; 0];
-            tspan = [0; 1e11];
+            tspan = [0, 40];
 
             obj = obj@otp.robertson.RobertsonProblem(tspan, y0, params);
         end

toolbox/+otp/+robertson/+presets/ROBER.m

@@ -0,0 +1,29 @@
+classdef ROBER < otp.robertson.RobertsonProblem
+    % The Robertson configuration from :cite:p:`HW96` (p. 144). This differs from :class:`Canonical` only in the time
+    % span which is extended to $[0, 10^{11}]$. This presents a challenge for numerical integrators to preserve solution
+    % positivity.
+    methods
+        function obj = ROBER
+            % Create the ROBER Robertson problem object.
+            %
+            % Parameters
+            % ----------
+            %
+            % Returns
+            % -------
+            % obj : RobertsonProblem
+            %    The constructed problem.
+            
+            params = otp.robertson.RobertsonParameters;
+            params.K1 = 0.04;
+            params.K2 = 3e7;
+            params.K3 = 1e4;
+            
+            y0 = [1; 0; 0];
+            tspan = [0; 1e11];
+            
+            obj = obj@otp.robertson.RobertsonProblem(tspan, y0, params);
+        end
+
+    end
+end