给定 X 计算 Sin Y（带偏移量）

Question

我有一个函数（从这里）计算给定 X 时的坐标 Y

function calculateSinYGivenX(time, frequency = 1, amplitude = 1, phase = 0, offset = 0) {
  return Math.sin((time * frequency * (Math.PI * 2)) + (phase * (Math.PI * 2))) * amplitude + offset; 
}

到目前为止，我的测试按预期

expect(calculateSinYGivenX(time = 0, frequency = 1, amplitude = 1, phase = 0, offset = 0)).toEqual(0);
expect(calculateSinYGivenX(time = 0.25, frequency = 1, amplitude = 1, phase = 0, offset = 0)).toEqual(1);
expect(calculateSinYGivenX(time = 0.5, frequency = 1, amplitude = 1, phase = 0, offset = 0)).toBeCloseTo(0);
expect(calculateSinYGivenX(time = 0.75, frequency = 1, amplitude = 1, phase = 0, offset = 0)).toEqual(-1);
expect(calculateSinYGivenX(time = 1, frequency = 1, amplitude = 1, phase = 0, offset = 0)).toBeCloseTo(0);

通过说明：

当我尝试将波向右移动时（phase = 0.5），他们失败了

expect(calculateSinYGivenX(time = 0, frequency = 1, amplitude = 1, phase = 0.5, offset = 0)).toEqual(-1);
expect(calculateSinYGivenX(time = 0, frequency = 1, amplitude = 1, phase = 1, offset = 0)).toEqual(0);
expect(calculateSinYGivenX(time = 0, frequency = 1, amplitude = 1, phase = 1.5, offset = 0)).toEqual(1);


Expected -1.2246467991473532e-16 to equal -1
Expected 2.4492935982947064e-16 to equal 0
Expected -3.6739403974420594e-16 to equal 1

说明：

不幸的是，我的数学不够好，无法找出我哪里出错了。我已经使用在线资源来达到这一点，但我似乎无法让它按预期工作。

Answer 1

经过阅读和测试一些内容后，阶段只是开始时间，因此可以将其理解为“时间偏移”。
因此，时间 + 相位的组合将始终给出相同的结果（对于固定频率、幅度和偏移）

例如：

console.log(calculateSinYGivenX(time = 0.25, frequency = 1, amplitude = 1, phase = 1.26, offset = 0));
console.log(calculateSinYGivenX(time = 1.26, frequency = 1, amplitude = 1, phase = 0.25, offset = 0));
console.log(calculateSinYGivenX(time = 1.50, frequency = 1, amplitude = 1, phase = 0.01, offset = 0));
=> 
-0.06279051952931265
-0.06279051952931265
-0.06279051952931265

因此，相位变量的情况按预期工作。

注意JS中的浮点变量句柄，你使用了toBeCloseTo(x)函数，所以我建议你使用它来进行比较。