Floating-point environment

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C++
 
Numerics的图书馆
常见的数学函数
浮点环境
复数
数字阵列
伪随机数生成
编译时合理的算法 （C++11）
通用的数值运算
Original:
Generic numeric operations
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iota（C++11）
accumulate
inner_product
adjacent_difference
partial_sum
 
浮点环境
功能
Original:
Functions
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feclearexcept（C++11）
fetestexcept（C++11）
feraiseexcept（C++11）
fegetexceptflag
fesetexceptflag		（C++11）
（C++11）
fegetround
fesetround		（C++11）
（C++11）
fegetenv
fesetenv		（C++11）
feholdexcept（C++11）
feupdateenv（C++11）
宏常量
Original:
Macro constants
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FE_ALL_EXCEPT
FE_DIVBYZERO
FE_INEXACT
FE_INVALID
FE_OVERFLOW
FE_UNDERFLOW		（C++11）
FE_DOWNWARD
FE_TONEAREST
FE_TOWARDZERO
FE_UPWARD		（C++11）
FE_DFL_ENV（C++11）
 
浮点环境的浮点状态标志的设置和控制方式实现支持。它是本地线程，每个线程都会继承父线程的初始状态，其浮点环境。浮点运算修改浮点状态标志，用于指示异常结果或辅助信息。浮点控制模式的状态会影响一些浮点运算的结果.
Original:
The floating-point environment is the set of floating-point status flags and control modes supported by the implementation. It is thread-local, each thread inherits the initial state of its floating-point environment from the parent thread. Floating-point operations modify the floating-point status flags to indicate abnormal results or auxiliary information. The state of floating-point control modes affects the outcomes of some floating-point operations.
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浮点环境访问和修改是唯一有意义的 #pragma STDC FENV_ACCESS设置为ON。否则，执行是免费的假设，浮点控制模式始终是默认的，浮点状态标志从来没有测试或修改。在实践中，一些现有的编译器支持#pragma明确，但大多数编译器允许反正有意义的访问浮点环境.
Original:
The floating-point environment access and modification is only meaningful when #pragma STDC FENV_ACCESS is set to ON. Otherwise the implementation is free to assume that floating-point control modes are always the default ones and that floating-point status flags are never tested or modified. In practice, few current compilers support the #pragma explicitly, but most compilers allow meaningful access to the floating-point environment anyway.
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目录

[编辑] 类型

Defined in header <cfenv>
fenv_t
类型代表整个浮点环境
Original:
The type representing the entire floating-point environment
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fexcept_t
该型集体所有的浮点状态标志
Original:
The type representing all floating-point status flags collectively
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[编辑] 功能

（C++11）
清除指定的浮点状态标志
Original:
clears the specified floating-point status flags
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（函数） [edit]
（C++11）
确定哪些指定浮点状态标志被设置
Original:
determines which of the specified floating-point status flags are set
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（函数） [edit]
（C++11）
提出了指定的浮点异常
Original:
raises the specified floating-point exceptions
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（函数） [edit]
（C++11）
（C++11）
复制或浮点环境指定的浮点状态标志的状态
Original:
copies the state of the specified floating-point status flags from or to the floating-point environment
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（函数） [edit]
（C++11）
（C++11）
获取或设置舍入的方向
Original:
gets or sets rounding direction
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（函数） [edit]
（C++11）
保存或恢复当前浮点环境
Original:
saves or restores the current floating point environment
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（函数） [edit]
（C++11）
保存环境，清除所有状态标志，而忽略了未来所有的错误
Original:
saves the environment, clears all status flags and ignores all future errors
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（函数） [edit]
（C++11）
浮点环境恢复和提高了先前抛出异常
Original:
restores the floating-point environment and raises the previously raise exceptions
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（函数） [edit]

[编辑] 宏

（C++11）
浮点异常
Original:
floating-point exceptions
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（宏不变） [edit]
（C++11）
浮点舍入方向
Original:
floating-point rounding direction
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（宏不变） [edit]
（C++11）
默认的浮点环境
Original:
default floating-point environment
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（宏不变） [edit]

[编辑] 注释

浮点异常无关的C + +异常。当浮点运算提出了一个浮点异常，浮点环境的变化，可以测试std::fetestexcept的状态，但在大多数实现中的C + +程序不间断地继续执行.
Original:
The floating-point exceptions are not related to the C++ exceptions. When a floating-point operation raises a floating-point exception, the status of the floating-point environment changes, which can be tested with std::fetestexcept, but the execution of a C++ program on most implementations continues uninterrupted.
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有编译器的扩展，可用于自动生成C + +异常的浮点异常时，提出：1
Original:
There are compiler extensions that may be used to generate C++ exceptions automatically whenever a floating-point exception is raised:
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  • GNU libc函数feenableexcept()可捕获浮点异常，产生的信号SIGFPE。如果-fnon-call-exceptions使用的编译器选项，信号的处理程序，可能会引发用户定义的C + +异常.
    Original:
    GNU libc function feenableexcept() enables trapping of the floating-point exceptions, which generates the signal SIGFPE. If the compiler option -fnon-call-exceptions was used, the handler for that signal may throw a user-defined C++ exception.
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  • 微软的WinAPI函数_control87()可捕获浮点异常，产生一个硬件异常，这可以被转换成C + +异常_set_se_translator.
    Original:
    Microsoft WinAPI function _control87() enables trapping of the floating-point exceptions, which generates a hardware exception, which can be converted to C++ exceptions with _set_se_translator.
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