Math.atan() 返回输入

发布于 2024-10-20 00:08:33 字数 458 浏览 4 评论 0原文

我在 Math.atan 返回与输入相同的值时遇到问题。

public double inchToMOA( double in, double range){
        double rangeIn = 36*range;
        double atan = (in / rangeIn) * -1.0;
        double deg = Math.atan(atan);
        double moa = deg * 60;
        return moa;
    }

我将所有这些都放在一行中，但我将其分解为不同的变量，看看是否能找出它不起作用的原因。如果 in = -10 且 range = 300，则 atan 约为 -.00094。角度应约为 -.053 度，但 math.atan 返回 -.00094，与输入相同。

我的数字对于 math.atan 来说太小了吗？

原文

I'm having a problem with Math.atan returning the same value as the input.

public double inchToMOA( double in, double range){
        double rangeIn = 36*range;
        double atan = (in / rangeIn) * -1.0;
        double deg = Math.atan(atan);
        double moa = deg * 60;
        return moa;
    }

I had this all in one line, but I broke it down into different variables to see if I could find out why it wasn't working. if in = -10 and range = 300, then atan is about -.00094. The angle should be about -.053 degrees, but math.atan is returning -.00094, the same as the input.

Is my number too small for math.atan?

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酷炫老祖宗 2024-10-27 00:08:33

反正切在这里描述：

http://mathworld.wolfram.com/InverseTangent.html

我不知道不认为你的论点是这里的问题。

当然，您意识到计算机三角函数处理的是弧度而不是度数，对吧？

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等风也等你 2024-10-27 00:08:33

可能只是这样。如果您查看数学中正切函数的严格定义，您会发现对于较小的“x”值，tan(x) = sin(x)/cos(x)

lim x->0, sin(x) = x
lim x->0, cos(x) = 1

因此，您可以看到 lim x->0, tan(x) -> x 表示它的倒数，arctan，返回给定的值。至于 Math.atan 的数值准确性，我认为作者已经竭尽全力确保其数值准确性。

It might just be. If you look at the strict definition of the tangent function in mathematics what you see if that tan(x) = sin(x)/cos(x) for small values of "x"

lim x->0, sin(x) = x
lim x->0, cos(x) = 1

hence, you could see that lim x->0, tan(x) -> x meaning that it's inverse, arctan, returns the value it is given. As to the numerical accuracy of Math.atan I would think that the authors had gone to great lengths to ensure it's numerical accuracy.

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