为什么这个罪的方法返回一个错误的答案？ [英] why is this sin method returning a wrong answer?

问题描述

嘿，工作在一些类别，我碰到一个奇怪的问题，基本上扩大计算器类添加一些trig方法，我得到一个不正确的值，当我调用sin方法在返回形式一个双。我发送一个值100.7到方法，它返回0.168231，从我可以看到正确的值应该是= 0.939693或有abouts。

继承代码，我

（感谢）

http://files.me.com/knyck2/svpfd4

  // 
 // Calculator_trig.m 
 // 11.4_calculator_trig 
 // 
 //由Nicholas Iannone创建1 / 6/10。 
 //版权所有2010 __MyCompanyName__。版权所有。 
 // 
 
 #importCalculator_trig.h
 #import< math.h> 
 
 @implementation计算器（三角函数）
 
  - （double）sin 
 {
 double result; 
 
 result =（double）sin（accum）; 
 
返回结果; 
 
} 
  - （double）cos 
 {
 double result; 
 
 result = cos（accum）; 
 
返回结果; 
} 
  - （double）tan 
 {
 double result; 
 
 result = tan（accum）; 
 
返回结果; 
} 
 
 @end 
 
 #importCalculator.h
 
 
 @implementation计算器
  - （void）setAccumulator：（double）value 
 {
 accumulator = value; 
} 
 
  - （void）clear 
 {
 accumulator = 0; 
} 
 
  - （double）accumulator 
 {
 return accum; 
} 
 
  - （double）memoryClear 
 {
 memory = 0; 
 NSLog（@memory has been cleared）; 
 return accum; 
} 
 
  - （double）memoryStore 
 {
 memory = accum; 
 NSLog（@内存已设置为％g，内存）; 
 return accum; 
} 
 
  - （double）memoryRecall 
 {
 accumulator = memory; 
 NSLog（@累计器已设置为％g，累加器）; 
 return accum; 
} 
 
  - （double）memoryAdd 
 {
 memory + = accumulator; 
 NSLog（@accumulator：％g已添加到内存，内存现在为％g，累加器，内存）; 
 return accum; 
} 
 
  - （double）memorySubtract 
 {
 memory  -  = accumulator; 
 NSLog（@accumulator：％g已从内存中减去，内存现在为％g，累加器，内存）; 
 return accum; 
} 
 
  - （double）add：（double）value 
 {
 accumulator + = value; 
 return accum; 
} 
 
  - （double）subtract：（double）value 
 {
 accumulator  -  = value; 
 return accum; 
} 
 
  - （double）multiply：（double）value 
 {
 accumulator * = value; 
 return accum; 
} 
 
  - （double）divide：（double）value 
 {
 accumulator / = value; 
 return accum; 
} 
 
  - （double）changeSign 
 {
 accumulator = -accumulator; 
 return accum; 
} 
 
  - （double）reciprocal 
 {
 accumulator = 1 / accumulator; 
 return accum; 
} 
 
  - （双）xSquared 
 {
累加器* =累加器; 
 return accum; 
} 
 @end 
 
 #import< Foundation / Foundation.h> 
 #importCalculator.h
 #importCalculator_trig.h
 
 int main（int argc，const char * argv []）{
 NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; 
 
计算器* myCalc = [[Calculator alloc] init]; 
 
 double a = 0; 
 
 [myCalc setAccumulator：100.70]; 
 a = [myCalc sin]; 
 
 NSLog（@sin of accumulator =％f，a）; 
 
 [myCalc release]; 
 [pool drain]; 
 return 0; 
} 
  

解决方案

100.7弧度，给出的答案是正确的。

Hey, working on some categories and I've bumped up against a weird issue, im basically expanding on a calculator class to add some trig methods, and i am getting an incorrect value when i call the sin method in the return in the form of a double. i send a value of 100.7 to the method and it returns 0.168231, from what i can see the correct value should be = 0.939693 or there abouts.

heres the code, I'm also attaching a link to the full project here:

(thanks)

http://files.me.com/knyck2/svpfd4

//
//  Calculator_trig.m
//  11.4_calculator_trig
//
//  Created by Nicholas Iannone on 1/6/10.
//  Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import "Calculator_trig.h"
#import <math.h>

@implementation Calculator (Trigonometry)

-(double) sin
{
 double result;

 result =   (double) sin (accumulator);

 return result;

}
-(double) cos
{
 double result;

 result =  cos ( accumulator);

 return result;
}
-(double) tan
{
 double result;

 result =  tan ( accumulator);

 return result;
}

@end

    #import "Calculator.h"


@implementation Calculator
-(void) setAccumulator: (double) value
{
 accumulator = value;
}

-(void) clear
{
 accumulator = 0;
}

-(double) accumulator
{
 return accumulator;
}

-(double) memoryClear
{
 memory = 0;
 NSLog(@"memory has been cleared");
 return accumulator;
}

-(double) memoryStore
{
 memory = accumulator;
 NSLog(@"memory has been set to %g", memory);
 return accumulator;
}

-(double) memoryRecall
{
 accumulator = memory;
 NSLog(@"accumulator has been set to %g", accumulator);
 return accumulator;
}

-(double) memoryAdd
{
 memory += accumulator;
 NSLog(@"accumulator: %g has been added to memory, memory is now %g", accumulator, memory);
 return accumulator;
}

-(double) memorySubtract
{
 memory -= accumulator;
 NSLog(@"accumulator: %g has been subtracted from memory, memory is now %g", accumulator, memory);
 return accumulator;
}

-(double) add: (double) value
{
 accumulator += value;
 return accumulator;
}

-(double) subtract: (double) value
{
 accumulator -= value;
 return accumulator;
}

-(double) multiply: (double) value
{
 accumulator *= value;
 return accumulator;
}

-(double) divide: (double) value
{
 accumulator /= value;
 return accumulator;
}

-(double) changeSign
{
 accumulator = -accumulator; 
 return accumulator;
}

-(double) reciprocal
{
 accumulator = 1 / accumulator;
 return accumulator;
}

-(double) xSquared
{
 accumulator *= accumulator;
 return accumulator;
}
@end

    #import <Foundation/Foundation.h>
#import "Calculator.h"
#import "Calculator_trig.h"

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    Calculator *myCalc = [[Calculator alloc] init];

 double a = 0;

 [myCalc setAccumulator: 100.70];
 a = [myCalc sin];

 NSLog(@" sin of accumulator = %f", a);

 [myCalc release];
    [pool drain];
    return 0;
}

解决方案

You are computing the sin of 100.7 radians, and the answer given is the correct one.

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