Question

I am trying to draw the cos curve using javascript. I expected to see a nice cos curve going accross the webpage. like this…

I added 200 to move the curve down so I could see the whole thing. I multiply by 100 because there are no decimal places in html. If you look at the jsfiddle it is a mess

http://jsfiddle.net/RN7WN/8/

$(function(){    
    for (i=0; i<500; i++){ 
        var el = $('<div class="dot"></div>'); 
        var y = Math.cos(i*100) * 100 + 200;
        var x = i ;
        el.css({ 'left' : x+'px' , 'top':y+ 'px'});
        $('#main').after(el);  
    } 
});​

Answer 1

Trigonometric functions use radians, not degrees. To convert between degrees and radians, use the formula

radians = Math.PI / 180 * degrees

Here’s an updated version of the fiddle that shows something recognizable.