pro parabola
x=[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0]
y=[8.8,21.6,32.4,51.2,72.0,94.8,125.6,156.4]

result=poly_fit(x,y,2);拟合抛物线
x1=max(x)*randomu(10,1000)
y1=result[2]*x1^2+result[1]*x1+result[0]

print,'y=',result[2],'x^2+',result[1],'x+',result[0]
set_plot,'PS'
filename='f:parabola.eps'
device,file=filename,/ENCAPSULATED,/COLOR, BITS=8,xsize=xsize,ysize=ysize
plot,x,y,psym=4,symsize=1,xrange=[0,10],yrange=[0,160]
oplot,x1,y1,psym=3,symsize=0.1
device,/CLOSE

END

输出的结果y=      1.82143x^2+      4.57381x+      3.32143

画出来的图

带权重的抛物线拟合：Result = POLYFITW(X, Y, Weights,2)