octave:2> persona.nome='Marco'
persona =

  scalar structure containing the fields:

    nome = Marco

octave:3> persona.cognome='Caliari'
persona =

  scalar structure containing the fields:

    nome = Marco
    cognome = Caliari

octave:4> persona.anni=20
persona =

  scalar structure containing the fields:

    nome = Marco
    cognome = Caliari
    anni =  20

octave:5> persona.anni+2
ans =  22
octave:6> persona.matrice=rand(2,2)
persona =

  scalar structure containing the fields:

    nome = Marco
    cognome = Caliari
    anni =  20
    matrice =

       0.86161   0.79991
       0.12030   0.23032


octave:7> isfield(persona,'nome')
ans =  1
octave:8> isfield(persona,'Nome')
ans = 0
octave:9> k=0.1
k =  0.10000
octave:10> 0+k
ans =  0.10000
octave:11> ans+k
ans =  0.20000
octave:12> ans+k
ans =  0.30000
octave:13> ans+k
ans =  0.40000
octave:14> ans+k
ans =  0.50000
octave:15> ans+k
ans =  0.60000
octave:16> ans+k
ans =  0.70000
octave:17> ans+k
ans =  0.80000
octave:18> ans+k
ans =  0.90000
octave:19> ans+k
ans =  1.00000
octave:20> 1==ans
ans = 0
octave:21> odefun = @(t,y) y;
octave:22> y0=1;
octave:23> tspan=[0,1];
octave:24> options.InitialStep=0.25;
octave:25> [tout,yout]=rk2(odefun,tspan,y0,options);
octave:26> tout
tout =

   0.00000
   0.25000
   0.50000
   0.75000
   1.00000

octave:27> yout
yout =

   1.0000
   1.2812
   1.6416
   2.1033
   2.6949

octave:28> abs(exp(1)-yout(end))
ans =  0.023426
octave:29> options.InitialStep=0.25^2;
octave:30> [tout,yout]=rk2(odefun,tspan,y0,options);
octave:31> yout
yout =

   1.0000
   1.0645
   1.1331
   1.2061
   1.2838
   1.3666
   1.4547
   1.5484
   1.6482
   1.7544
   1.8675
   1.9879
   2.1160
   2.2524
   2.3976
   2.5521
   2.7166

octave:32> abs(exp(1)-yout(n))
error: `n' undefined near line 32 column 17
error: evaluating argument list element number 1
error: evaluating argument list element number 1
octave:32> abs(exp(1)-yout(end))
ans =  0.0016883
octave:33> 0.023426/0.0016883
ans =  13.875
octave:34> 1/k^2
ans =  100.00
octave:35> k
k =  0.10000
octave:36> 1/0.25^2
ans =  16
octave:37> options.InitialStep=0.125;
octave:38> [tout,yout]=rk2(odefun,tspan,y0,options);
octave:39> abs(exp(1)-yout(end))
ans =  0.0064406
octave:40> options.InitialStep=0.125/2;
octave:41> [tout,yout]=rk2(odefun,tspan,y0,options);
octave:42> abs(exp(1)-yout(end))
ans =  0.0016883
octave:43> ans/0.0064406
ans =  0.26213
octave:44> 0.0064406/0.0016883
ans =  3.8148
octave:45> options.InitialStep=0.125/2;
octave:46> [tout,yout]=rk2(odefun,tspan,y0,options);
octave:47> abs(exp(1)-yout(end))
ans =  0.0016883
octave:48> options.InitialStep=0.125/4;
octave:49> [tout,yout]=rk2(odefun,tspan,y0,options);
octave:50> abs(exp(1)-yout(end))
ans =  4.3215e-04
octave:51> 0.0016883/ans
ans =  3.9067
octave:52> odefun=@(t,y) t;
octave:53> options.InitialStep=0.125/2;
octave:54> [tout,yout]=rk2(odefun,tspan,y0,options);
octave:55> abs(1/2-yout(end))
ans =  1
octave:56> y0=0
y0 = 0
octave:57> [tout,yout]=rk2(odefun,tspan,y0,options);
octave:58> abs(1/2-yout(end))
ans = 0
octave:59> odefun = @(t,y) y;
octave:60> options.InitialStep=0.3;
octave:61> [tout,yout]=rk2(odefun,tspan,1,options);
octave:62> tout
tout =

   0.00000
   0.30000
   0.60000
   0.90000
   1.00000

octave:63> diary off