Reorganized File Structure

Added Documentation

MathKit/MPFactorialTerm.m

@@ -0,0 +1,32 @@
+//
+//  MPFactorialTerm.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 15.11.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPFactorialTerm.h"
+
+@implementation MPFactorialTerm
+
+- (instancetype)initWithTerm:(MPTerm *)term
+{
+    self = [super init];
+    if (self) {
+        NSAssert(term != nil, @"term must not be nil.");
+        _term = term;
+    }
+    return self;
+}
+
+- (NSDecimalNumber *)doEvaluation:(NSError *__autoreleasing *)error
+{
+    NSDecimalNumber *value = [self.term evaluate:error];
+    if (!value) {
+        return nil;
+    }
+    return [[NSDecimalNumber alloc] initWithDouble:tgamma(value.doubleValue + 1)];
+}
+
+@end