How to create a function that lets me choose the output (euler,Rk2 or Rk4)?

Hi guys, I have made an Euler solution, an RK2 and an RK4 solution for the same differential equation and now i want to put these all in one function so that i can choose from the command line which solution i want. I have tried several things, but I can't figure it out. Can anyone help me?

These are the codes for Euler, RK2 and RK4:

% Euler
function x = EULER(k,M,h,D) % Euler's method
...
return

% Runge Kutta 2
function x = rk2(k,M,N,D) % midpoint rule
..
return

% Runge Kutta 4
function x = rk4(k,M,N,D)
...
return

Answer 1

[Cris LaPierre]

All your functions have 4 inputs and one output, so that works out nicely. I would probably create a function declaration with a 5th input for indicating the method to use. For simplicity, I'll keep the other inputs the same. Use a switch statement on method and either call the appropriate function or copy the code for that function into the case. For conciseness, this calls the existing functions.

function x = mySolver(k,M,h,D,method)
switch lower(method)
    case 'euler'
        x = EULER(k,M,h,D); % Euler's method
    end
    case 'rk2'    
        x = rk2(k,M,h,D) % Runge Kutta 2
    end
    case 'rk4'    
        x = rk2(k,M,h,D) % Runge Kutta 2
    end
end 

It would then be called doing something like

x = mySolver(k,M,h,D,'euler')

Answer 2

[madhan ravi]

https://www.mathworks.com/help/matlab/ref/varargout.html

Answer 3

[TADA]

Easiest Solution Would Be:

function x = solveDiffEq(k, M, step, D, method)
    if nargin < 5; method = 'euler'; end
    
    switch lower(method)
        case 'euler' 
            x = EULER(k, M, step, D);
        case 'rk2'
            x = rk2(k, M, step, D);
        case 'rk4'
            x = rk4(k, M, step, D);
    end
end

Now EULER IS The Default Method For solving, And If Specified Uses The Specified Method.