1. The problem statement, all variables and given/known data I have two questions: 1) If i have two first order ODE y(1) and y(2) (in terms of time), i know how to plot y(1) versus time and y(2) versus time but i dont know how to plot y(2) versus y(1) 2)I have two second order ODES X''=... and Z''=... to solve this, we make the substitutions y(1)=X, y(2)=X', y(3)=Z, and y(4)=Z' then we have two first order ODEs: y(2)'=... and y(4)'=... I typed this into Matlab (dydt=[(the equation for y(2)'; the equation for y(4)']) but an error came up since i didnt define y(4). how do i do this? 2. Relevant equations 3. The attempt at a solution 1) i tried putting: plot(y(1),y(:,2)), and i also tried plot(y(1),y(2)) but these didnt work. Any help would be very much appreciated. Than you.