%PENG4.1
clear all; 
clc;

step = 0.5;
t=-9:step:9;
Y = [];

for i=1:length(t)
   if t(i)>=0.0
       y=-3*t(i)^2+5;
   else
       y=3*t(i)^2+5;  
   end
  Y = [Y;y];
end
   
plot(t,Y, 0,5, 'r*');