反正切函数

实现定点DSP汇编层反正切函数的差分进化算法

Implementation of arc tangent function using assembly in fixed-point DSP based on differential evolution algorithm

与传统方法相比，差分进化算法求得的逼近多项式精度高、阶数小，设计出的反正切函数实时性远优于C库函数。

Compared with traditional methods , the approximating polynomial calculated by DE is of high accuracy and low order , and the real-time behavior of the arc tangent function designed by DE is much better than C library function .

对LMS算法做了改进得到了一种新的基于反正切函数的变步长LMS算法，新算法只有一个参数需要确定其范围，形式简单，方便使用。

Improving LMS algorithm . There is only one parameter needed to determine its scope , so this new algorithm has simple form and is convenient to use .

基于差分进化算法，提出一种在定点DSP汇编层快速实现高精度反正切函数的方法，并对该方法在确定精度范围内的正确性和实时性进行了测试。

Based on differential evolution ( DE ) algorithm , a method of fast implementation of the arc tangent function with high accuracy using assembly in fixed-point DSP is proposed . The validity and real-time behavior of this method is tested in a large scale .

实验结果表明了图像采集系统能够实时采集CMOS图像传感器输出的图像数据，仿真结果表明Stokes矢量和反正切函数计算算法是正确的。

The result of the experiment shows that real time image collecting system could collect image data from CMOS sensor in real-time . Stokes vector and reverse tangent function computing arithmetic is proven to be correct by the result of simulation .

由于CORDIC算法能把复杂的反正切函数求解和角度旋转操作转化为简单的移位和加法操作，文中所给出的同步模型可在数字域同时完成频率偏移估计和频率偏移校正。

Because the CORDIC algorithm can change the arctan function and round of angle to addition and shift operation , the novel model presented in the paper can complete frequency offset estimation and correction in digital field in the same time .

论文分析传统叠加平均算法并指出该算法的局限，对残留干扰噪声及潜伏期的扰动问题，提出一种基于反正切函数的IIR滤波器叠加平均算法。

Thesis analyzes superposition average algorithm of tradition and pointed out the limitations of the algorithm , the problems about that the residual interference noise and the incubation period of disturbance , proposes a superposition averaging algorithm based on the arc tangent function of the IIR filter .

本文对常用的反正切函数进行了分析，利用分段直线对其进行拟合，提出了一种浮点运算变定点运算的快速算法。

A fast algorithm uses sub section lines to near some functions of arc tangent .

定义了不同的强度-相位转换方式，例如线性方式、对数函数方式、正切函数方式、反正切函数方式等。

Various conversion manners are defined , including linearity , logarithm function , tangent function and arc tangent function .

该优化算法根据反正切函数本身的对称性，能够极大地减少反正切运算耗费的硬件资源。

Because the arc tangent reduced look-up table ( LUT ) bulk , the optimization algorithm greatly saved the hardware resources .

本文通过对反算坐标方位角的数学模型进行分析，得出反正切函数是最佳反算直线坐标方位角数学模型的结论。

Through the analysis of the mathematical model of anti-calculating the azimuth of straight line with coordinate , the optimal mathematical model of anti-calculating the azimuth of straight line is anti-tangent function .

结果表明，与已有的修正反正切函数或双曲函数模型相比，该模型不仅具有较高的精度，而且对变压器饱和特性的模拟也更为合理。

The results show that the model has good fitting precision . It is more reasonable than traditional modified arc tangent function or hyperbolic function model for the saturation characteristic of transformer .

提出了双光路光学电流传感器检测方法及其数据处理方法，即激光输出功率保持不变时，可采用双光路结构和反正切函数处理方法求出待测脉冲大电流。

Measuring technology and data processing method of two-path optical current sensor were proposed . High pulse current could be measured by two-path configuration and arc-tangential function processing method with the constant output power of laser .

文献[5]中提出的奇点问题是由原表达式中的反正切函数引起的，而在做全空间研究的时候发现，自然对数函数也会引起奇点问题。

The analytic odd points put forward in Literature [ 11 ] is caused by the anti-trigonometric function in the forward theoretical expressions , and discover at the time of doing whole spaces to study , the natural logarithms function will also cause the analytic odd points .

为此，我们基于反正切函数设计一种新型非线性灰度变换函数，综合运用台风云图的信息熵和标准差构造台风云图质量的评价函数，然后利用差分演化算法获得非线性灰度变换参数。

Therefore , we design a new non-linear gray transformation function based on arc-tangent curve , and construct quality evaluation function of typhoon cloud image by using image information entropy and standard deviation , then we use the differential evolution algorithm to achieve the parameter of non-linear gray transformation algorithm .