使用js画图之正弦曲线

//画正弦曲线
//dot 原点
//amplitude 振幅 — A
//initialPhase 初相 — φ
//setover 偏距 — k
//palstance 角速度 — ω
//len 周期数
function drawSinusoid(dot, amplitude,initialPhase,palstance,setover, len, opts){
var color = opts&&opts.color?opts.color:"DarkRed"; //曲线的颜色
var max = len*2*Math.PI/w; //x的最大值
//var x = -2*Math.PI/w/3;
var x = 0; //x的初值
var pre = [dot[0]+x, dot[1]+(amplitude*Math.sin(palstance*x+initialPhase)+setover)]; //y的初值
for(;x < max;x+=5){ //每五个单位画一条线
var cur = [dot[0]+x, dot[1]+(amplitude*Math.sin(palstance*x+initialPhase)+setover)];
drawLine(pre, cur, {color: color}); // 画线
pre = cur;
}
var d = Math.PI/(2*w);
for(var x =0;x < max;x+=d){//描点
var cur = [dot[0]+x, dot[1]+(amplitude*Math.sin(palstance*x+initialPhase)+setover)];
drawPoint({
pw:3,ph:3,color:'DarkRed',point: cur
});
}

var pend = [dot[0]+max, dot[1]+(amplitude*Math.sin(palstance*max+initialPhase)+setover)];
drawPoint({
pw:3,ph:3,color:'DarkRed',point: pend
});
drawLine(pre, pend);
}