`if statement` code snippets in matlab

if norm([x y z])<1000 error('error: for near surface coordinates only'); end in matlab

where when x<0 y=100, when x is between 0 and 50 y=2(x+200), when x is between 50 and 100 y= (3x-(x/20)+10) and when x is over 100 y=299 in matlab