Add Root Function and Product Function

MathKit/MPProductFunction.h

@@ -0,0 +1,70 @@
+//
+//  MPProductFunction.h
+//  MathPad
+//
+//  Created by Kim Wittenburg on 10.01.15.
+//  Copyright (c) 2015 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPFunction.h"
+
+
+/*!
+ @header
+ This file contains the <code>MPProductFunction</code> class.
+ */
+
+
+
+@class MPProductFunction, MPExpression;
+
+
+/*!
+    @class      MPProductFunction
+    @abstract   This class represents a product function (generally noted using a
+                capital pi).
+ 
+    @discussion A product function has a start and a target expression indicating
+                how often the product expression should be evaluated. Both the
+                value of the start expression and the target expressions are
+                included in the iterations.
+ 
+                Each iteration the iteration value is incremented by
+                <code>1</code>. If the start and target expression evaluate to
+                the same value the product is evaluated once.
+ */
+@interface MPProductFunction : MPFunction
+
+/*!
+    @property   startExpression
+    @abstract   The value of the first iteration.
+ 
+    @discussion The start expression must define a variable that may be used in
+                the sum expression. If the start expression does not define a
+                variable the product function will not be evaluatable.
+ */
+@property (nonatomic, strong) MPExpression *startExpression; /* Index 0 */
+
+
+/*!
+    @property   targetExpression
+    @abstract   The value if the last iteration.
+ 
+    @discussion The target expression must not define a variable.
+ */
+@property (nonatomic, strong) MPExpression *targetExpression; /* Index 1 */
+
+
+/*!
+    @property   productExpression
+    @abstract   The product expression evaluated multiple times.
+ 
+    @discussion During evaluation of the product expression the variable defined
+                in the start expression is available. That variable always
+                contains the value of the current iteration.
+ 
+                The product expression itself must not define a variable.
+ */
+@property (nonatomic, strong) MPExpression *productExpression; /* Index 2 */
+
+@end