Starting diary file "diary-2016-02-17.txt" on Wed Feb 17 2016 12:29 PM.

swinger
swinger(0,2)

help ode23tx
 ODE23TX  Solve non-stiff differential equations.  Textbook version of ODE23.
 
    ODE23TX(F,TSPAN,Y0) with TSPAN = [T0 TFINAL] integrates the system
    of differential equations dy/dt = f(t,y) from t = T0 to t = TFINAL.
    The initial condition is y(T0) = Y0.
...

clc
edit f
timespan = [0 10]
timespan =
     0    10
initial = 1
initial =
     1
ode23tx(@f,timespan,initial)

xlabel('time t')
ylabel('function values y(t)')
shg

exp( 10/2)
ans =
  148.4132

edit f   % Change to ydot = -y/2;
ode23tx(@f,timespan,initial)

edit f   % Change to ydot = t/2;
ode23tx(@f,timespan,initial)
ode23tx(@f,timespan,0)

[T,Y] = ode23tx(@f,timespan,0);
whos
  Name           Size            Bytes  Class     Attributes

  T             11x1                88  double              
  Y             11x1                88  double              
  ans            1x1                 8  double              
  initial        1x1                 8  double              
  timespan       1x2                16  double              

clear

edit mylotka

ode23tx(@mylotka,[0 20],[300 ; 150])

legend('rabbits','foxes')
xlabel('time')
ylabel('population')
shg

ode23tx(@mylotka,[0 20],[15;22])
ode23tx(@mylotka,[0 20],[102 ; 198])
ode23tx(@mylotka,[0 20],[100 ; 200])
ode23tx(@mylotka,[0 20],[2 ; 1000])

[T,Y] = ode23tx(@mylotka,[0 20],[300 ; 150]);
whos
  Name        Size            Bytes  Class     Attributes

  T         128x1              1024  double              
  Y         128x2              2048  double              

T
T =
         0
    0.0400
    0.1649
    0.2967
    ...
   19.7745
   19.9030
   20.0000

Y
Y =
  300.0000  150.0000
  305.2997  162.6736
  310.7456  211.3861
  293.5273  276.8071
  ...
  249.9890   98.2983
  280.9754  121.6589
  299.7222  146.3971

size(Y)
ans =
   128     2

plot(Y(:,1),Y(:,2)),shg
xlabel('rabbits'); ylabel('foxes')
title('Phase Space Plot')
shg

edit weightf.m
ode23tx(@weightf, [0 20], [1/2 ; 0])