1008 syms r(t) theta(t) m g L
 1009 L = 2*m*diff(r)^2
 1010 L = 2*m*diff(r)^2 + m/2*r^2*diff(theta)^2-g*r*m(3-cos(theta))
 1011 L = 2*m*diff(r)^2 + m/2*r^2*diff(theta)^2-g*r*m(3-(theta))
 1012 L = 2*m*diff(r)^2 + m/2*r^2*diff(theta)^2- g*r*m*(3-cos(theta))
 1013 L
 1014 man diff
 1015 help diff
 1016 diff(L, theta)
 1017 diff(L)
 1018 diff(L, theta)
 1019 theta
 1020 diff(L, theta, t)
 1021 diff(L, theta)
 1022 diff(L, t, theta)
 1023 who
 1024 L
 1025 diff(L, theta, r, theta)
 1026 L
 1027 L = 2*m*diff(r)^2 + m/2*r^2*diff(theta)^2- g*r*m*(3-cos(theta))
 1028 clear
 1029 syms m g theta r L
 1030 syms t
 1031 theta = sym('theta(t)')
 1032 r = sym('r(t)')
 1033 L = 2*m*diff(r,t)^2 + m/2*r^2*diff(theta,t)^2- g*r*m*(3-cos(theta,t))
 1034 diff(diff(L,diff(theta)),t)
 1035 diff(diff(L,diff(theta)),t)
 1036 diff(diff(L,diff(theta)),t) - diff(L, theta)
 1037 diff(diff(L,diff(theta,t)),t) - diff(L, theta)
 1038 simplify(diff(diff(L,diff(theta,t)),t) - diff(L, theta))
 1039 diff(L,diff(theta,t))
 1040 diff(L,theta)
 1041 diff(diff(L,diff(theta,t)),t)
 1042 sym('diff(diff(L,diff(theta,t)),t) = 0'
 1043 )
 1044 sym('diff(diff(L,diff(theta,t)),t) = 0')