使用SIN和COS函数迭代时，NAN会导致

Nan results when iterating using sin and cos functions

本文关键字：NAN 迭代 SIN COS 函数 使用      更新时间：2023-10-16

我正在使用代码:: blocks 10.05编译此程序，但是通常我会在每次输出中开始生产NAN之前完成大约10次迭代。我想知道这是否是使用COS和SIN功能引起的问题，以及是否有不错的工作来避免这种情况？

我必须生产很多迭代，因为我正在研究大学项目，因此它也必须准确。我查找了一些有关如何避免使用罪和cos的文章，尽管我需要严格遵循一些公式，否则我产生的结果可能不准确，所以我不确定是否要妥协。

    struct Particle // Need to define what qualities our particle has
{
   double dPosition;
   double dAngle;
};
Particle Subject;
void M1(double &x, double &y) //Defines movement if particle doesn't touch inner   boundary
{
    x = x + 2*y;
}
double d = 0.25; //This can and will be changed when I need to find a distance between
                // the two cricles at a later stage

void M2(double &x,double &y, double d) //Defines movement of a particle if it impacts the inner boundary
{
    double z = asin(-(sin(y)+d*cos(x + y))/0.35);
    double y1 = y;
    y = asin(-0.35*sin(z) + d*cos(x + y + 2*z));
    x = y + y1 + x + 2*z;
}
int main()
{
    cout << "Please tell me where you want this particle to start positions-wise? (Between 0 and 2PI" << endl;
    cin >> Subject.dPosition;
    cout << "Please tell me the angle that you would like it to make with the normal? (Between 0 and PI/2)" << endl;
    cin >> Subject.dAngle;
    cout << "How far would you like the distances of the two middle circles to be?" << endl;
    double d;
    cin >> d;
    // These two functions are to understand where the experiment begins from.
    // I may add a function to change where the circle starts however I will use radius = 0.35 throughout
    cout << "So position is: " << Subject.dPosition << endl;
    cout << "And angle with the normal is: " << Subject.dAngle <<endl;
    int n=0;
    while (n <= 100) //This is used to iterate the process and create an array of Particle data points
    {               // in order to use this data to build up Poincare diagrams.
    {
        while (Subject.dPosition > 2*M_PI)
            Subject.dPosition = Subject.dPosition - 2*M_PI;
    }
    {
        if (0.35 >= abs(0.35*cos(Subject.dPosition + Subject.dAngle)+sin(Subject.dAngle))) //This is the condition of hitting the inner boundary
            M2(Subject.dPosition, Subject.dAngle, d); //Inner boundary collision
        else
            M1(Subject.dPosition, Subject.dAngle); // Outer boundary collision
    };
    cout << "So position is: " << Subject.dPosition << endl;
    cout << "And angle with the normal is: " << Subject.dAngle <<endl;
    n++;
}
    return 0;
}

Nan在C 中显示为无限数字的无限偏差和其他某些非代表性数字的指示。

编辑：

正如Matteo Itallia所指向的，inf用于无限/零分割。我发现这些方法：

template<typename T>
inline bool isnan(T value) {
    return value != value;
}
// requires #include <limits>
template<typename T>
inline bool isinf(T value) {
    return std::numeric_limits<T>::has_infinity &&
        value == std::numeric_limits<T>::infinity();
}

参考：http：//bytes.com/topic/c/answers/588254-how-check-check-check-double-nan

如果该值不在[-1， 1]之外，并且传递给Asin（），则结果为NAN

如果您需要检查NAN，请尝试以下

if( value != value ){
    printf("value is nann");
}
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