我在 C++ 中进行定点实现，我正在尝试定义“非数字”并支持一个函数 bool isnan(…)，如果数字不是数字则返回 true，否则返回 false。
有人能给我一些关于如何在我的定点数学实现中定义“非数字”和实现函数 bool isnan( ... ) 的想法吗？
我已经阅读了有关 C++ Nan 的信息，但我无法获得有关如何手动定义和创建函数 nan() 以在定点实现中使用它的任何来源或参考。
有人可以告诉我如何进行或提供一些参考来继续吗？
谢谢
更新定点标头
#ifndef __fixed_point_header_h__
#define __fixed_point_header_h__
#include <boost/operators.hpp>
#include <boost/assert.hpp>
#endif
namespace fp {
template<typename FP, unsigned char I, unsigned char F>
class fixed_point: boost::ordered_field_operators<fp::fixed_point<FP, I, F> >
{
//compute the power of 2 at compile time by template recursion
template<int P,typename T = void>
struct power2
{
static const long long value = 2 * power2<P-1,T>::value;
};
template <typename P>
struct power2<0, P>
{
static const long long value = 1;
};
fixed_point(FP value,bool): fixed_(value){ } // initializer list
public:
typedef FP base_type; /// fixed point base type of this fixed_point class.
static const unsigned char integer_bit_count = I; /// integer part bit count.
static const unsigned char fractional_bit_count = F; /// fractional part bit count.
fixed_point(){ } /// Default constructor.
//Integer to Fixed point
template<typename T> fixed_point(T value) : fixed_((FP)value << F)
{
BOOST_CONCEPT_ASSERT((boost::Integer<T>));
}
//floating point to fixed point
fixed_point(float value) :fixed_((FP)(value * power2<F>::value)){ }
fixed_point(double value) : fixed_((FP)(value * power2<F>::value)) { }
fixed_point(long double value) : fixed_((FP)(value * power2<F>::value)) { }
/// Copy constructor,explicit definition
fixed_point(fixed_point<FP, I, F> const& rhs): fixed_(rhs.fixed_)
{ }
// copy-and-swap idiom.
fp::fixed_point<FP, I, F> & operator =(fp::fixed_point<FP, I, F> const& rhs)
{
fp::fixed_point<FP, I, F> temp(rhs); // First, make a copy of the right-hand side
swap(temp); //swapping the copied(old) data the new data.
return *this; //return by reference
}
/// Exchanges the elements of two fixed_point objects.
void swap(fp::fixed_point<FP, I, F> & rhs)
{
std::swap(fixed_, rhs.fixed_);
}
bool operator <(
/// Right hand side.
fp::fixed_point<FP, I, F> const& rhs) const
{
return fixed_ < rhs.fixed_; //return by value
}
bool operator ==(
/// Right hand side.
fp::fixed_point<FP, I, F> const& rhs) const
{
return fixed_ == rhs.fixed_; //return by value
}
// Addition.
fp::fixed_point<FP, I, F> & operator +=(fp::fixed_point<FP, I, F> const& summation)
{
fixed_ += summation.fixed_;
return *this; //! /return A reference to this object.
}
/// Subtraction.
fp::fixed_point<FP, I, F> & operator -=(fp::fixed_point<FP, I, F> const& subtraction)
{
fixed_ -= subtraction.fixed_;
return *this; // return A reference to this object.
}
// Multiplication.
fp::fixed_point<FP, I, F> & operator *=(fp::fixed_point<FP, I, F> const& factor)
{
fixed_ = ( fixed_ * (factor.fixed_ >> F) ) +
( ( fixed_ * (factor.fixed_ & (power2<F>::value-1) ) ) >> F );
return *this; //return A reference to this object.
}
/// Division.
fp::fixed_point<FP, I, F> & operator /=(fp::fixed_point<FP, I, F> const& divisor)
{
fp::fixed_point<FP, I, F> fp_z=1;
fp_z.fixed_ = ( (fp_z.fixed_) << (F-2) ) / ( divisor.fixed_ >> (2) );
*this *= fp_z;
return *this; //return A reference to this object
}
private:
/// The value in fixed point format.
FP fixed_;
};
} // namespace fmpl
#endif
#endif // __fixed_point_header__