53 lines
1.4 KiB
Objective-C
53 lines
1.4 KiB
Objective-C
//
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// MPPowerFunction.m
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// MathPad
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//
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// Created by Kim Wittenburg on 30.09.14.
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// Copyright (c) 2014 Kim Wittenburg. All rights reserved.
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//
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#import "MPPowerFunction.h"
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#import "MPExpression.h"
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#import "MPExpressionTree.h"
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@implementation MPPowerFunction
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MPFunctionAccessorImplementation(ExponentExpression, _exponentExpression)
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- (NSArray *)childrenAccessors
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{
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return @[@"exponentExpression"];
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}
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- (BOOL)validate:(NSError *__autoreleasing *)error
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{
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if (!self.baseValue) {
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if (error) {
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*error = MPParseError(11,
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NSLocalizedString(@"No Base For Power.", @"Error message. This is displayed when a power does not have a base value."),
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nil);
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}
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return NO;
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}
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return [self.baseValue validate:error] && [[self.exponentExpression parse] validate:error];
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}
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- (NSDecimalNumber *)evaluate
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{
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NSDecimalNumber *base = [self.baseValue evaluate];
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NSDecimalNumber *exponent = [[self.exponentExpression parse] evaluate];
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if ([base isEqualToNumber:@(0)] && [exponent isEqualToNumber:@(0)]) {
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// The C pow function returns 1 for pow(0, 0). Mathematically this should be undefined.
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return [NSDecimalNumber notANumber];
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}
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return [[NSDecimalNumber alloc] initWithDouble:pow(base.doubleValue, exponent.doubleValue)];
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}
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- (NSString *)description
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{
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return [NSString stringWithFormat:@"^%@", self.exponentExpression.description];
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}
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@end
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