//pointArrayX,pointArrayY 为两个数组,分别为x轴对应的点和y轴对应的点
function getEquationPara(pointArrayX, pointArrayY) { var abr = []; var xavg = eval(pointArrayX.join("+")) / pointArrayX.length; var yavg = eval(pointArrayY.join("+")) / pointArrayY.length; var a, b, r; var xysum = 0, xxsum = 0; var divider = 0, dividend = 0, xxavgsum = 0, yyavgsum = 0; for (var i = 0; i < pointArrayX.length; i++) { xysum += pointArrayX[i] * pointArrayY[i]; xxsum += pointArrayX[i] * pointArrayX[i]; dividend += (pointArrayX[i] - xavg) * (pointArrayY[i] - yavg); xxavgsum += (pointArrayX[i] - xavg) * (pointArrayX[i] - xavg); yyavgsum += (pointArrayY[i] - yavg) * (pointArrayY[i] - yavg); } b = (xysum - pointArrayX.length * xavg * yavg) / (xxsum - (pointArrayX.length * xavg * xavg)); a =fomatFloat(PointFloat(yavg - b * xavg,4),3);//fomatFloat--四舍六入方法,查看详细
if (a==0) { a = "0.0"; } b = fomatFloat(b, 4); divider = fomatFloat(Math.sqrt(xxavgsum) * Math.sqrt(yyavgsum), 5); r = dividend / divider; abr.push(a); abr.push(b); abr.push(r.toString().substr(0, 6)); return abr; }
function PointFloat(src, pos) {
return Math.round(src * Math.pow(10, pos)) / Math.pow(10, pos);
}