_vx = _V*Math.cos(Math.atan((initMouseY - (initY+RADIUS/2))/(initMouseX - (initX+RADIUS/2)))); _vy = _V*Math.sin(Math.atan((initMouseY - (initY+ RADIUS/2))/(initMouseX - (initX+RADIUS/2))));

这是一段代码，它计算了一个速度向量的两个分量 _vx 和 _vy。这个速度向量用于控制某个物体（例如子弹、小球等）的运动轨迹，使其沿着从起始点到鼠标位置的方向运动。具体的计算方法如下：

首先，计算从起始点到鼠标位置的方向角度。这里使用了 Math.atan 函数来计算反正切值，其参数为鼠标位置和起始点位置的坐标差值比值，可以得到一个介于 -π/2 和 π/2 之间的角度值。

然后，根据速度大小（_V）和方向角度，计算出速度向量的两个分量 _vx 和 _vy。这里使用了 Math.cos 和 Math.sin 函数分别计算余弦值和正弦值，再乘以速度大小即可得到分量值。

最终，可以将这两个分量作为物体的速度向量，用于控制其运动轨迹。

相关问题

// Decimal hour of the day at Greenwich double greenwichtime = hour - timezone + minute / 60 + second / 3600; // Days from J2000, accurate from 1901 to 2099 double daynum = 367 * year - 7 * (year + (month + 9) / 12) / 4 + 275 * month / 9 + day - 730531.5 + greenwichtime / 24; //Mean longitude of the sun double mean_long = daynum * 0.01720279239 + 4.894967873; double mean_anom = daynum * 0.01720197034 + 6.240040768; double eclip_long = mean_long + 0.03342305518 * Math.sin(mean_anom) + 0.0003490658504 * Math.sin(2 * mean_anom); double obliquity = 0.4090877234 - 0.000000006981317008 * daynum; double rasc = Math.atan2(Math.cos(obliquity) * Math.sin(eclip_long), Math.cos(eclip_long)); double decl = Math.asin(Math.sin(obliquity) * Math.sin(eclip_long)); double sidereal = 4.894961213 + 6.300388099 * daynum + rlon; double hour_ang = sidereal - rasc; double elevation = Math.asin(Math.sin(decl) * Math.sin(rlat) + Math.cos(decl) * Math.cos(rlat) * Math.cos(hour_ang)); //Local azimuth of the sun double azimuth = Math.atan2(-Math.cos(decl) * Math.cos(rlat) * Math.sin(hour_ang), Math.sin(decl) - Math.sin(rlat) * Math.sin(elevation)); azimuth = into_range(Math.toDegrees(azimuth), 0, 360); elevation = into_range(Math.toDegrees(elevation), -180, 180);抽出常量

您可以将这些常量提取出来，并使用它们来计算方位角（azimuth）和仰角（elevation）。以下是一个示例代码：

import java.util.TimeZone;

public class Main {
    private static final double MEAN_LONGITUDE_OFFSET = 4.894967873;
    private static final double MEAN_ANOMALY_COEFFICIENT = 0.01720197034;
    private static final double ECLIPTIC_LONGITUDE_COEFFICIENT_1 = 0.03342305518;
    private static final double ECLIPTIC_LONGITUDE_COEFFICIENT_2 = 0.0003490658504;
    private static final double OBLIQUITY_COEFFICIENT_1 = 0.4090877234;
    private static final double OBLIQUITY_COEFFICIENT_2 = 0.000000006981317008;
    private static final double SIDEREAL_COEFFICIENT_1 = 4.894961213;
    private static final double SIDEREAL_COEFFICIENT_2 = 6.300388099;

    public static void main(String[] args) {
        // 其他变量的定义和赋值

        // Decimal hour of the day at Greenwich
        double greenwichtime = hour - timezone + minute / 60 + second / 3600;

        // Days from J2000, accurate from 1901 to 2099
        double daynum = 367 * year - 7 * (year + (month + 9) / 12) / 4 + 275 * month / 9 + day - 730531.5 + greenwichtime / 24;

        //Mean longitude of the sun
        double mean_long = daynum * MEAN_ANOMALY_COEFFICIENT + MEAN_LONGITUDE_OFFSET;

        double mean_anom = daynum * MEAN_ANOMALY_COEFFICIENT + 6.240040768;

        double eclip_long = mean_long + ECLIPTIC_LONGITUDE_COEFFICIENT_1 * Math.sin(mean_anom) + ECLIPTIC_LONGITUDE_COEFFICIENT_2 * Math.sin(2 * mean_anom);

        double obliquity = OBLIQUITY_COEFFICIENT_1 - OBLIQUITY_COEFFICIENT_2 * daynum;

        double rasc = Math.atan2(Math.cos(obliquity) * Math.sin(eclip_long), Math.cos(eclip_long));

        double decl = Math.asin(Math.sin(obliquity) * Math.sin(eclip_long));

        double sidereal = SIDEREAL_COEFFICIENT_1 + SIDEREAL_COEFFICIENT_2 * daynum + rlon;

        double hour_ang = sidereal - rasc;

        double elevation = Math.asin(Math.sin(decl) * Math.sin(rlat) + Math.cos(decl) * Math.cos(rlat) * Math.cos(hour_ang));

        //Local azimuth of the sun
        double azimuth = Math.atan2(-Math.cos(decl) * Math.cos(rlat) * Math.sin(hour_ang), Math.sin(decl) - Math.sin(rlat) * Math.sin(elevation));

        azimuth = into_range(Math.toDegrees(azimuth), 0, 360);
        elevation = into_range(Math.toDegrees(elevation), -180, 180);

        // 其他操作
    }

    private static double into_range(double value, double min, double max) {
        double range = max - min;
        return ((value - min) % range + range) % range + min;
    }
}

这样，您可以在计算方位角和仰角时直接使用这些常量，使代码更加易读和易于维护。

else: self.total_N = 1000 self.beta_0 = continuous_beta_0 self.beta_1 = continuous_beta_1 self.cosine_s = 0.008 self.cosine_beta_max = 999. self.cosine_t_max = math.atan(self.cosine_beta_max * (1. + self.cosine_s) / math.pi) * 2. * (1. + self.cosine_s) / math.pi - self.cosine_s self.cosine_log_alpha_0 = math.log(math.cos(self.cosine_s / (1. + self.cosine_s) * math.pi / 2.)) self.schedule = schedule if schedule == 'cosine': # For the cosine schedule, T = 1 will have numerical issues. So we manually set the ending time T. # Note that T = 0.9946 may be not the optimal setting. However, we find it works well. self.T = 0.9946 else: self.T = 1.解析

这段代码是某个类的初始化方法，它设置了该类的一些属性值。其中包括总迭代次数、beta_0、beta_1、cosine_s、cosine_beta_max、cosine_t_max、cosine_log_alpha_0、schedule和T等属性。如果schedule属性的值是'cosine'，则设定T属性为0.9946，否则设为1。这段代码的目的是为了初始化该类的属性，为后续的操作做好准备。