C图书馆数学。h函数-yiteyi-C++库

这个 数学H header定义了各种数学函数和一个宏。这个库中所有可用的函数都需要 双重的 作为论据和回报 双重的 结果呢。让我们逐一讨论一些重要的功能。 1. 双层天花板（双层x） ：C库函数double ceil（double x）返回大于或等于x的最小整数值。

null

syntax : double ceil(double x)

C

                         // C code to illustrate                       
                         // the use of ceil function.                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                         float                                     val1, val2, val3, val4;                       
           
                         val1 = 1.6;                       
                         val2 = 1.2;                       
                         val3 = -2.8;                       
                         val4 = -2.3;                       
           
                         printf                                     (                                     "value1 = %.1lf"                                     ,                                     ceil                                     (val1));                       
                         printf                                     (                                     "value2 = %.1lf"                                     ,                                     ceil                                     (val2));                       
                         printf                                     (                                     "value3 = %.1lf"                                     ,                                     ceil                                     (val3));                       
                         printf                                     (                                     "value4 = %.1lf"                                     ,                                     ceil                                     (val4));                       
                                   
                         return                                     (0);                       
                         }                       

输出：

value1 = 2.0value2 = 2.0value3 = -2.0value4 = -2.0

2. 双层（双x）： C库函数double floor（double x）返回小于或等于x的最大整数值。

syntax : double floor(double x)

C

                         // C code to illustrate                       
                         // the use of floor function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 float                                     val1, val2, val3, val4;                       
           
                                                 val1 = 1.6;                       
                                                 val2 = 1.2;                       
                                                 val3 = -2.8;                       
                                                 val4 = -2.3;                       
           
                                                 printf                                     (                                     "Value1 = %.1lf"                                     ,                                     floor                                     (val1));                       
                                                 printf                                     (                                     "Value2 = %.1lf"                                     ,                                     floor                                     (val2));                       
                                                 printf                                     (                                     "Value3 = %.1lf"                                     ,                                     floor                                     (val3));                       
                                                 printf                                     (                                     "Value4 = %.1lf"                                     ,                                     floor                                     (val4));                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

Value1 = 1.0Value2 = 1.0Value3 = -3.0Value4 = -3.0

3. 双晶圆厂（双x） ：C库函数double fabs（double x）返回x的绝对值。

syntax : double fabs(double x)

C

                         // C code to illustrate                       
                         // the use of fabs function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 int                                     a, b;                       
                                                 a = 1234;                       
                                                 b = -344;                       
                                   
                                                 printf                                     (                                     "The absolute value of %d is %lf"                                     , a,                                     fabs                                     (a));                       
                                                 printf                                     (                                     "The absolute value of %d is %lf"                                     , b,                                     fabs                                     (b));                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

The absolute value of 1234 is 1234.000000The absolute value of -344 is 344.000000

4. 双对数（双x） ：C库函数double log（double x）返回x的自然对数（base-e对数）。

syntax : double log(double x)

C

                         // C code to illustrate                       
                         // the use of log function                       
           
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 double                                     x, ret;                       
                                                 x = 2.7;                       
           
                                                 /* finding log(2.7) */                       
                                                 ret =                                     log                                     (x);                       
                                                 printf                                     (                                     "log(%lf) = %lf"                                     , x, ret);                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

log(2.700000) = 0.993252

5. 双对数10（双x） ：C库函数double log10（double x）返回x的公共对数（以10为底的对数）。

syntax : double log10(double x)

C

                         // C code to illustrate                       
                         // the use of log10 function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 double                                     x, ret;                       
                                                 x = 10000;                       
                                   
                                                 /* finding value of log1010000 */                       
                                                 ret =                                     log10                                     (x);                       
                                                 printf                                     (                                     "log10(%lf) = %lf"                                     , x, ret);                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

log10(10000.000000) = 4.000000

6. 双fmod（双x，双y） ：C库函数double fmod（double x，double y）返回x除以y的余数。

syntax : double fmod(double x, double y)

C

                         // C code to illustrate                       
                         // the use of fmod function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 float                                     a, b;                       
                                                 int                                     c;                       
                                                 a = 8.2;                       
                                                 b = 5.7;                       
                                                 c = 3;                       
                                                 printf                                     (                                     "Remainder of %f / %d is %lf"                                     , a, c,                                     fmod                                     (a, c));                       
                                                 printf                                     (                                     "Remainder of %f / %f is %lf"                                     , a, b,                                     fmod                                     (a, b));                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

Remainder of 8.200000 / 3 is 2.200000Remainder of 8.200000 / 5.700000 is 2.500000

7. 双sqrt（双x） ：C库函数double sqrt（double x）返回x的平方根。

syntax : double sqrt(double x)

C

                         // C code to illustrate                       
                         // the use of sqrt function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
           
                                                 printf                                     (                                     "Square root of %lf is %lf"                                     , 225.0,                                     sqrt                                     (225.0) );                       
                                                 printf                                     (                                     "Square root of %lf is %lf"                                     , 300.0,                                     sqrt                                     (300.0) );                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

Square root of 225.000000 is 15.000000Square root of 300.000000 is 17.320508

8. 双功率（双x，双y） ：C库函数double pow（double x，double y）将x提升为y的幂，即xy。

syntax : double pow(double x, double y)

C

                         // C code to illustrate                       
                         // the use of pow function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 printf                                     (                                     "Value 8.0 ^ 3 = %lf"                                     ,                                     pow                                     (8.0, 3));                       
           
                                                 printf                                     (                                     "Value 3.05 ^ 1.98 = %lf"                                     ,                                     pow                                     (3.05, 1.98));                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

Value 8.0 ^ 3 = 512.000000Value 3.05 ^ 1.98 = 9.097324

9 double modf（双x，双*整数） ：C库函数double modf（double x，double*integer）返回小数部分（小数后的部分），并将整数设置为整数部分。

syntax : double modf(double x, double *integer)

C

                         // C code to illustrate                       
                         // the use of modf function                       
                         #include<stdio.h>                       
                         #include<math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 double                                     x, fractpart, intpart;                       
           
                                                 x = 8.123456;                       
                                                 fractpart =                                     modf                                     (x, &intpart);                       
           
                                                 printf                                     (                                     "Integral part = %lf"                                     , intpart);                       
                                                 printf                                     (                                     "Fraction Part = %lf "                                     , fractpart);                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

Integral part = 8.000000Fraction Part = 0.123456

10 双经验（双x） ：C库函数double exp（double x）返回提升到第x次方的e值。

syntax : double exp(double x)

下面的代码代表

C

                         // C code to illustrate                       
                         // the use of exp function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 double                                     x = 0;                       
                                   
                                                 printf                                     (                                     "The exponential value of %lf is %lf"                                     , x,                                     exp                                     (x));                       
                                                 printf                                     (                                     "The exponential value of %lf is %lf"                                     , x+1,                                     exp                                     (x+1));                       
                                                 printf                                     (                                     "The exponential value of %lf is %lf"                                     , x+2,                                     exp                                     (x+2));                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

The exponential value of 0.000000 is 1.000000The exponential value of 1.000000 is 2.718282The exponential value of 2.000000 is 7.389056

11 双cos（双x） ：C库函数double cos（double x）返回弧度角x的余弦。

syntax : double cos(double x)

注：同样的语法也可用于其他三角函数，如sin、tan等。

C

                         // C code to illustrate                       
                         // the use of cos function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         #define PI 3.14159265                       
           
                         int                                     main ()                       
                         {                       
                                                 double                                     x, ret, val;                       
           
                                                 x = 60.0;                       
                                                 val = PI / 180.0;                       
                                                 ret =                                     cos                                     ( x*val );                       
                                                 printf                                     (                                     "The cosine of %lf is %lf degrees"                                     , x, ret);                       
                                   
                                                 x = 90.0;                       
                                                 val = PI / 180.0;                       
                                                 ret =                                     cos                                     ( x*val );                       
                                                 printf                                     (                                     "The cosine of %lf is %lf degrees"                                     , x, ret);                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

The cosine of 60.000000 is 0.500000 degreesThe cosine of 90.000000 is 0.000000 degrees

12 双ACO（双x）： C库函数double acos（double x）返回x的弧度余弦。

syntax : double acos(double x)

注：同样的语法也可用于其他圆弧三角函数，如asin、atan等。

C

                         // C code to illustrate                       
                         // the use of acos function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         #define PI 3.14159265                       
           
                         int                                     main ()                       
                         {                       
                                                 double                                     x, ret, val;                       
           
                                                 x = 0.9;                       
                                                 val = 180.0 / PI;                       
           
                                                 ret =                                     acos                                     (x) * val;                       
                                                 printf                                     (                                     "The arc cosine of %lf is %lf degrees"                                     , x, ret);                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

The arc cosine of 0.900000 is 25.855040 degrees

13 双谭（双x）： C库函数double tanh（double x）返回x的双曲正切。

syntax : double tanh(double x)

注：同样的语法也可用于其他双曲三角函数，如sinh、cosh等。

C

                         // C code to illustrate                       
                         // the use of tanh function                       
                         #include <stdio.h>                       
                         #include <math.h>                       
           
                         int                                     main ()                       
                         {                       
                                                 double                                     x, ret;                       
                                                 x = 0.5;                       
           
                                                 ret =                                     tanh                                     (x);                       
                                                 printf                                     (                                     "The hyperbolic tangent of %lf is %lf degrees"                                     , x, ret);                       
                                   
                                                 return                                     (0);                       
                         }                       

输出：

The hyperbolic tangent of 0.500000 is 0.462117 degrees

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