Javascript中带有加号-减号（±）的极坐标曲线方程-Polarcurveequationwithplus-minussign(±)inJavascript

I am trying to draw polar curves on HTML canvas using Javascript. What should I do when I want to convert plus-minus sign (±)?

我试图使用Javascript在HTML画布上绘制极坐标曲线。当我想转换加号 - 减号(±)时,我该怎么办?

Example: Watt's curve

示例:瓦特的曲线

Below is what I tried. Since I need to get value of r, I enclose entire equation with square root, also I use it's absolute value, otherwise I get null for trying to get square root if number is negative. Following code draws something that looks like a polar curve, but not Watt's curve.

以下是我的尝试。因为我需要获得r的值,所以我用方根包含整个方程式,我也使用它的绝对值,否则如果数字为负则我得到null以获得平方根。下面的代码绘制的东西看起来像极地曲线,但不是瓦特的曲线。

var a = 1;
var b = 1;
var c = 2;
r = Math.sqrt(Math.abs(Math.pow(b, 2) - Math.pow(a * Math.sin(t) * Math.sqrt(Math.abs(Math.pow(c, 2) - Math.pow(a, 2) * Math.pow(Math.cos(t), 2), 2)), 2) ));

I get similar deviations of expected results with other equations containing plus-minus sign (ones without it work fine), so I suppose the problem is that I wrongly 'translate' this symbol. What do I do wrong?

我得到类似的预期结果偏差与其他包含正负号的方程式(没有它的方法工作正常),所以我想问题是我错误地“翻译”了这个符号。我做错了什么?

1 个解决方案

var a = 1;
var b = 1;
var c = 2;

var b2 = Math.pow(b, 2);
var asint = a * Math.sin(t);
var sqroot = Math.sqrt(Math.pow(c, 2) - Math.pow(a, 2) * Math.pow(Math.cos(t), 2), 2);

var r = Math.sqrt(b2 - Math.pow(asint + sqroot, 2));
// now plot r
r = Math.sqrt(b2 - Math.pow(asint - sqroot, 2));
// now plot r again