Add validators for numeric values including symbolic

Author: Steven-Roberts

src/+otp/+utils/+validation/isNumerical.m

@@ -0,0 +1,5 @@
+function result = isNumerical(x)
+
+result = isnumeric(x) || isa(x, 'sym');
+
+end

src/+otp/+utils/+validation/mustBeNumerical.m

@@ -0,0 +1,7 @@
+function mustBeNumerical(x)
+
+if ~otp.utils.validation.isNumerical(x)
+    throwAsCaller(MException('OTP:notNumeric', 'Value must be numeric.'));
+end
+
+end

src/+otp/Problem.m

@@ -121,11 +121,11 @@ function validateNewState(obj, newTimeSpan, newY0, newParameters)
             % Ensures the TimeSpan, Y0, and Parameters are valid
             if length(newTimeSpan) ~= 2
                 error('TimeSpan must be a vector of two times');
-            elseif ~(isnumeric(newTimeSpan) || isa(newTimeSpan, 'sym'))
+            elseif ~otp.utils.validation.isNumerical(newTimeSpan)
                 error('TimeSpan must be numeric');
             elseif ~iscolumn(newY0)
                 error('Y0 must be a column vector');
-            elseif ~(isnumeric(newY0) || isa(newY0, 'sym'))
+            elseif ~otp.utils.validation.isNumerical(newY0)
                 error('Y0 must be numeric');
             elseif ~(isempty(obj.ExpectedNumVars) || length(newY0) == obj.ExpectedNumVars)
                 error('Expected Y0 to have %d components but has %d', obj.ExpectedNumVars, length(newY0));