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Objective-C常用數學常量宏及函數

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  • 数学常量:

    #define M_E         2.71828182845904523536028747135266250   // e
    
    #define M_LOG2E     1.44269504088896340735992468100189214   // log 2e
    
    #define M_LOG10E    0.434294481903251827651128918916605082  // log 10e
    
    #define M_LN2       0.693147180559945309417232121458176568  // log e2
    
    #define M_LN10      2.30258509299404568401799145468436421   // log e10
    
    #define M_PI        3.14159265358979323846264338327950288   // pi
    
    #define M_PI_2      1.57079632679489661923132169163975144   // pi/2
    
    #define M_PI_4      0.785398163397448309615660845819875721  // pi/4
    
    #define M_1_PI      0.318309886183790671537767526745028724  // 1/pi
    
    #define M_2_PI      0.636619772367581343075535053490057448  // 2/pi
    
    #define M_2_SQRTPI  1.12837916709551257389615890312154517   // 2/sqrt(pi)
    
    #define M_SQRT2     1.41421356237309504880168872420969808   // sqrt(2)
    
    #define M_SQRT1_2   0.707106781186547524400844362104849039  // 1/sqrt(2)
    


  • 常用函数:

    //指数运算
    
    NSLog(@"%.f", pow(3,2) ); //result 9
    
    NSLog(@"%.f", pow(3,3) ); //result 27
    
    
    //开平方运算
    
    NSLog(@"%.f", sqrt(16) ); //result 4
    
    NSLog(@"%.f", sqrt(81) ); //result 9
    
    
    //上舍入
    
    NSLog(@"res: %.f", ceil(3.000000000001)); //result 4
    
    NSLog(@"res: %.f", ceil(3.00)); //result 3
    
    
    //下舍入
    
    NSLog(@"res: %.f", floor(3.000000000001)); //result 3
    
    NSLog(@"res: %.f", floor(3.9999999)); //result 3
    
    
    //四舍五入
    
    NSLog(@"res: %.f", round(3.5)); //result 4
    
    NSLog(@"res: %.f", round(3.46)); //result 3
    
    NSLog(@"res: %.f", round(-3.5)); //NB: this one returns -4
    
    
    //最小值
    
    NSLog(@"res: %.f", fmin(5,10)); //result 5
    
    
    //最大值
    
    NSLog(@"res: %.f", fmax(5,10)); //result 10
    
    
    //绝对值
    
    NSLog(@"res: %.f", fabs(10)); //result 10
    
    NSLog(@"res: %.f", fabs(-10)); //result 10
    

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