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MQL5参考标准常量，列举和架构命名常量数学常量 

数学常量

特殊常量包含价值为数学表达式保留，这些常量可以在程序中的任意位置使用，使用 mathematical functions 取代计算值。

常量

描述

值

M_E

e

2.71828182845904523536

M_LOG2E

log2(e)

1.44269504088896340736

M_LOG10E

log10(e)

0.434294481903251827651

M_LN2

ln(2)

0.693147180559945309417

M_LN10

ln(10)

2.30258509299404568402

M_PI

pi

3.14159265358979323846

M_PI_2

pi/2

1.57079632679489661923

M_PI_4

pi/4

0.785398163397448309616

M_1_PI

1/pi

0.318309886183790671538

M_2_PI

2/pi

0.636619772367581343076

M_2_SQRTPI

2/sqrt(pi)

1.12837916709551257390

M_SQRT2

sqrt(2)

1.41421356237309504880

M_SQRT1_2

1/sqrt(2)

0.707106781186547524401

示例：

//+------------------------------------------------------------------+
//| 脚本程序启动函数                                                   |
//+------------------------------------------------------------------+
void OnStart()
  {
//--- 打印常量值
   Print("M_E = ",DoubleToString(M_E,16));
   Print("M_LOG2E = ",DoubleToString(M_LOG2E,16));
   Print("M_LOG10E = ",DoubleToString(M_LOG10E,16));
   Print("M_LN2 = ",DoubleToString(M_LN2,16));
   Print("M_LN10 = ",DoubleToString(M_LN10,16));
   Print("M_PI = ",DoubleToString(M_PI,16));
   Print("M_PI_2 = ",DoubleToString(M_PI_2,16));
   Print("M_PI_4 = ",DoubleToString(M_PI_4,16));
   Print("M_1_PI = ",DoubleToString(M_1_PI,16));
   Print("M_2_PI = ",DoubleToString(M_2_PI,16));
   Print("M_2_SQRTPI = ",DoubleToString(M_2_SQRTPI,16));
   Print("M_SQRT2 = ",DoubleToString(M_SQRT2,16));
   Print("M_SQRT1_2 = ",DoubleToString(M_SQRT1_2,16));
  }