polyfit.m

x = [50,50,100,150,200,250,300,350,400,450,500,550,600,650,700,750,800,850,900,950,1000,1050,1100,1150,1200,1250,1300,1350,1400,1450,1500,1550,1600,1650,1700,1750,1800,1850,1900,1950]
y = [635,633,630,627,621,612,603,597,594,594,599,614,635,644,666,694,733,747,748,748,749,749,750,750,749,749,746,738,730,722,714,706,697,690,686,682,681,681,681,681]
n = 6

p = polyfit (x, y, n)
f = polyout(p, 'x')
fplot(f, [min(x),max(x)])