edit
% Modify expression to add input arguments.
% Example:
%   a = [1 2 3; 4 5 6]; 
%   foo(a);

ms2

ans =

    6.8358

% Modify expression to add input arguments.
% Example:
%   a = [1 2 3; 4 5 6]; 
%   foo(a);

ms2

ans =

    0.4456

% Modify expression to add input arguments.
% Example:
%   a = [1 2 3; 4 5 6]; 
%   foo(a);

ms2

ans =

    0.7897

% Modify expression to add input arguments.
% Example:
%   a = [1 2 3; 4 5 6]; 
%   foo(a);

ms2

ans =

    6.8358

% Modify expression to add input arguments.
% Example:
%   a = [1 2 3; 4 5 6]; 
%   foo(a);

ms2

ans =

   8.5093e+25

options.InitialStep=0.1

options = 

    InitialStep: 0.1000

options.name="Marco"
??? options.name="Marco"
                 |
Error: The input character is not valid in
MATLAB statements or expressions.

options.name='Marco'

options = 

    InitialStep: 0.1000
           name: 'Marco'

f=@(t,y) y;
y0=1;
tspan=[0,1];
[tout,yout]=rk2(f,tspan,y0);
tout

tout =

         0
    0.0500
    0.1000
    0.1500
    0.2000
    0.2500
    0.3000
    0.3500
    0.4000
    0.4500
    0.5000
    0.5500
    0.6000
    0.6500
    0.7000
    0.7500
    0.8000
    0.8500
    0.9000
    0.9500
    1.0000

yout

yout =

    1.0000
    1.0513
    1.1051
    1.1618
    1.2213
    1.2839
    1.3497
    1.4189
    1.4916
    1.5680
    1.6484
    1.7329
    1.8217
    1.9150
    2.0132
    2.1164
    2.2248
    2.3388
    2.4587
    2.5847
    2.7172

yout(end)-exp(1)

ans =

   -0.0011

abs(yout(end)-exp(1))

ans =

    0.0011

[tout,yout]=rk2(f,tspan,y0);
opzioni.InitialStep=0.1;
[tout,yout]=rk2(f,tspan,y0,opzioni);
tout'

ans =

  Columns 1 through 4

         0    0.1000    0.2000    0.3000

  Columns 5 through 8

    0.4000    0.5000    0.6000    0.7000

  Columns 9 through 12

    0.8000    0.9000    1.0000    1.0000

abs(exp(1)-yout(end))

ans =

    0.0042

[tout,yout]=rk2(f,tspan,y0);
abs(exp(1)-yout(end))

ans =

    0.0011

opzioni.InitialStep=0.025;
[tout,yout]=rk2(f,tspan,y0,opzioni);
tout(2)

ans =

    0.0250

abs(exp(1)-yout(end))

ans =

   2.7788e-04

ans*4

ans =

    0.0011

opzioni.InitialStep=0.1;
[tout,yout]=rk2(f,tspan,y0,opzioni);
tout

tout =

         0
    0.1000
    0.2000
    0.3000
    0.4000
    0.5000
    0.6000
    0.7000
    0.8000
    0.9000
    1.0000
    1.0000

yout

yout =

    1.0000
    1.1050
    1.2210
    1.3492
    1.4909
    1.6474
    1.8204
    2.0116
    2.2228
    2.4562
    2.7141
    2.7141

format long e
tout

tout =

                         0
     1.000000000000000e-01
     2.000000000000000e-01
     3.000000000000000e-01
     4.000000000000000e-01
     5.000000000000000e-01
     6.000000000000000e-01
     7.000000000000000e-01
     7.999999999999999e-01
     8.999999999999999e-01
     9.999999999999999e-01
     1.000000000000000e+00

[tout,yout]=rk2(f,tspan,y0,opzioni);

k =

     1.000000000000000e-01


k =

     1.000000000000000e-01


k =

     1.000000000000000e-01


k =

     1.000000000000000e-01


k =

     1.000000000000000e-01


k =

     1.000000000000000e-01


k =

     1.000000000000000e-01


k =

     1.000000000000000e-01


k =

     1.000000000000000e-01


k =

     1.110223024625157e-16


k =

     0

[tout,yout]=rk2(f,tspan,y0,opzioni);
tout

tout =

                         0
     1.000000000000000e-01
     2.000000000000000e-01
     3.000000000000000e-01
     4.000000000000000e-01
     5.000000000000000e-01
     6.000000000000000e-01
     7.000000000000000e-01
     7.999999999999999e-01
     8.999999999999999e-01
     9.999999999999999e-01

t=0

t =

     0

k=0.1

k =

     1.000000000000000e-01

t=t+k

t =

     1.000000000000000e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     2.000000000000000e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     3.000000000000000e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     4.000000000000000e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     5.000000000000000e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     6.000000000000000e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     7.000000000000000e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     7.999999999999999e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     8.999999999999999e-01

k=min(k,1-t)

k =

     1.000000000000000e-01

t=t+k

t =

     9.999999999999999e-01

k=min(k,1-t)

k =

     1.110223024625157e-16

t=t+k

t =

     1

diary off