How does trig work in JavaScript? [closed]

问题

I have a value and its cosine as:

-0.2567721374914637
Cosine: -0.04253775592822526

Compare what we get in Python:

>>> import math
>>> math.cos(-0.2567721374914637)
0.9672147629178562

Is there a way I can do trig in JavaScript that isn't out to lunch?

Are there any math libraries or anything that provide working trigonometry?

--EDIT--

The code where I was getting the results reported were:

            var distance_along = (high_noon.getTime() / 1000 -
              summer_solstice.getTime() / 1000)
              / (winter_solstice.getTime() / 1000
              - summer_solstice.getTime() / 1000);
            console.log(distance_along);
            console.log('Cosine: ' + Math.cos(2 * Math.PI * distance_along));
            var added_degrees = (Math.cos(2 * Math.PI * distance_along) * 
              ANCIENT_CLOCK.earth_tilt);

That reported, for a distance along of

-0.2567721374914637
Cosine: -0.04253775592822526

Regarding the question of looking things up: I did not do extensive looking up of how to handle a cosine. I knew that JavaScript had a Math library, and thought the logical place to look for it was in Math.cos(). However, it reported the values above.

回答1:

You can do this javascript like this:

//Return the cosine of a number:
Math.cos(3);
// -0.9899924966004454

You can get the full list of Math objects here: JavaScript Math Object

回答2:

You have the Math object:

Math.cos(-0.25)
0.9689124217106447

You can find all functions available in Math here: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Math

来源：https://stackoverflow.com/questions/16387316/how-does-trig-work-in-javascript

标签

javascript

math

trigonometry