Added Lots of Documentation

Added some nice to haves
Improved and Unified General Code Layout

MathKit/MPFunctionTerm.h

@@ -8,6 +8,28 @@
 
 #import "MPTerm.h"
 
+/*!
+ @header
+ This file contains the <code>MPFunctionTerm</code> class.
+ */
+
+
+/*!
+    @define     MPEvaluateExpression
+    @abstract   Evaluates the receiver's child at the specified index and assigns
+                the evaluation result to a variable.
+ 
+    @discussion If errors occur during evaluation this macro returns
+                <code>nil</code>. Also there has to exist a <code>NSError *__autoreleasing *</code> pointer called <code>error</code>.
+ 
+    @param      var
+                The name of the variable that will be declared in this macro. It
+                will be of the type <code>NSDecimalNumber *</code> and contain
+                the result of the evaluation.
+ 
+    @param      index
+                The index of the child to be evaluated.
+ */
 #define MPEvaluateExpression(var, index) NSDecimalNumber *var = [[self expressionAtIndex:index] evaluate:error]; if (var == nil) return nil
 
 
@@ -15,11 +37,62 @@
 @class MPFunctionTerm, MPFunction, MPParsedExpression;
 
 
+/*!
+    @class      MPFunctionTerm
+    @abstract   A function term represents the term of a generic function.
+ 
+    @discussion This class is an abstract class that can not be evaluated. It is
+                the common superclass of all terms that represent <code>@link
+                //apple_ref/occ/cl/MPFunction@/link</code> instances.
+ */
 @interface MPFunctionTerm : MPTerm
 
+/*!
+    @method     initWithFunction:errors:
+    @abstract   Initializes a <code>MPFunctionTerm</code> from the specified
+                <code>@link //apple_ref/occ/cl/MPFunction@/link</code> instance.
+ 
+    @discussion This method parses the children of the specified
+                <code>function</code> and stores the respective parsed
+                expressions. They are accessible using the <code>@link
+                //apple_ref/occ/instm/MPFunctionTerm/expressionAtIndex:@/link</code>
+                method.
+ 
+                Whether the children should contain a variable definition is
+                determined using the <code>@link
+                //apple_ref/occ/instm/MPFunction/expectsVariableDefinitionInChildAtIndex:@/link</code>
+
+    @param      function
+                The function to initialize the receiver with. This method parses
+                the function's children. If any of them contain syntax errors
+                they are returned indirectly through the <code>errors</code>
+                parameter.
+ 
+    @param      errors
+                If any of the <code>function</code>'s children contain syntax
+                errors they are returned indirectly through this parameter. In
+                that case the method returns <code>nil</code>. If there are no
+                errors the parameter is not modified. This parameter is never set
+                to an empty array.
+ 
+    @return     A new <code>MPFunctionTerm</code> instance.
+ */
 - (instancetype)initWithFunction:(MPFunction *)function
                           errors:(NSArray *__autoreleasing *)errors; /* designated initializer */
 
+
+/*!
+    @method     expressionAtIndex:
+    @abstract   Returns a <code>@link
+                //apple_ref/occ/cl/MPParsedExpression@/link</code> instance that
+                represents the child at <code>anIndex</code> of the function that
+                is represented by the receiver.
+ 
+    @param      anIndex
+                The index of the child.
+ 
+    @return     A parsed expression that represents th
+ */
 - (MPParsedExpression *)expressionAtIndex:(NSUInteger)anIndex;
 
 @end