Combining multiple functions within one script

I have three functions I would like to put into one script. What would be the correct steps to do so. here are the following functions I have written.

function [] = gravitationalForce(m1,m2,d)
%{m1 = mass 1, m2 = mass 2, d = distance%}
G = 6.672 * 10^11;
syms F
F = (G*m1*m2/(d^2));
display(F)
end

function [] = velocityCalc(u,a,s)
%{u = velocity,a = acceleration,s = distance traveled%}
disp('V^2 =')
v = (u^2 + (2*a*s));
disp(v)
end

function [] = distanceTraveled(u,a,t)
%{u = velocity,a = acceleration,t = time%}
syms s
s = (u*t)+1/2*a*t^2;
display(s)
end

[Brooks Nelson]

I figured it out. If anyone was wandering I created another function physics with an end after all the full functions were inputed. This allowed me to call the function physics. I then can call each function within the function for an answer. Probably not the best way to do it but it worked for now.

function physics

function [] = gravitationalForce(m1,m2,d)
%{ m1 = mass 1,m2 = mass 2,d = distance%}

G = 6.672 * 10^11;

syms F

F = (G*m1*m2/(d^2));

display(F)

end

function [] = velocityCalc(u,a,s)

%{u = velocity,a = acceleration,s = distance traveled,%}

disp('V^2 =')

v = (u^2 + (2*a*s));

disp(v)

end

function [] = distanceTraveled(u,a,t)

%{u = velocity,a = acceleration,t = time%}

syms s

s = (u*t)+1/2*a*t^2;

display(s)

end

end

[Learner]

looks good but how to call a sub function within physcics function

[Walter Roberson]

The only ways to call a subfunction that is defined inside another function are:

1. Somehow obtain a handle to the subfunction. For example calling the wrapper function "physics" could return handles to the subfunctions; or

2. Have the wrapper function be a "switchyard" where you pass in information about which subfunction you want to call and the wrapper function calls it on your behalf. For example

function varargout = physics(request, varargin)
  switch request
     case 'grav'
       [varargout{1:nargout}] = GravitationalForce(varargin{:}) ;
   end

Invoke with

physics('grav', m1, m2, d)

[Kazi Newaz]

I get the error Undefined function or variable. What am I doing wrong?

function varargout = addcomp(request, varargin)
    function outc=addcomp1(z1,z2)
        realpart=real(z1)+real(z2);
        imagpart=imag(z1)+imag(z2);      
        outc=realpart+imagpart*1i;
        end
    function outc=addcomp2(z1,z2)
        outc=z1+z2;
        end
    switch request
        case 'addcomp1'
            [varargout{1:nargout}]=addcomp1(varargin{:});

        case 'addcomp2'
            [varargout{1:nargout}]=addcomp2(varargin{:});
    end
    
end

[Walter Roberson]

How are you invoking the function, and what is the complete error message?

[Kazi Newaz]

extremely sorry to have bothered you, it was an issue with me not having the path set up right, now it is working, thank you so much for the solution

Answer 1

[Mohammad Askari]

Another approach is to create a class with static methods with all your sub-functions. Save the following code as ALLFUNCS.m

classdef ALLFUNCS
    methods(Static)

          function result = SumElements(a,b,c)
              result = a + b + c;
          end

          function [prod,div] = MultiplyDivide(v1,v2,v3)
              prod = v1 * v2 * v3;
              div  = v1 / v2 / v3;
          end

    end
end

Then you can simply call the sub-functions like this:

s = ALLFUNCS.SumElements(3,4,5);
[p,d] = ALLFUNCS.MultiplyDivide(8,3,5);

[leanne dong]

this method does not seem to work for case where a function depends on the previous one.

Any suggestions?

[Mohammad Askari]

@leanne dong, it actually does. In the example below, the first function calls the other one. Is this what you are looking for?

classdef ALLFUNCS
    methods(Static)
        
          function result = SumElements(a,b,c)
              result = a + b + c;
              string = ALLFUNCS.IsGreaterThanZero(result);
              disp(['the answer is greater than zero: ',string]);
          end
          
          function str = IsGreaterThanZero(value)
              if value > 0
                  str = 'true';
              else
                  str = 'false';
              end
          end
          
    end
end

Answer 2

[Anders Bergåker]

Well, I find this limitation incredibly annoying so I use a workaround with the sfunc command. The first function takes the function you actually want to call as an argument. I've found this workaround ages ago, it might have some drawbacks I'm unaware of since I'm not an Matlab expert.

Put all this code in an .m file, eg. myLib.m which then will act as a function library. The call to use a specific function would then be:

     myLib('distanceTraveled', u, a, t)

It work fine with returnvalues as well. Examaple of myLib.m:

function varargout = sfunc(varargin)
   [varargout{1:nargout}] = feval(varargin{:});
end

function [] = gravitationalForce(m1,m2,d)
...
end

function [] = velocityCalc(u,a,s)
...
end

function [] = distanceTraveled(u,a,t)
...
end

[Rahul Gupta]

If I use this method. do I need to do any configuration for myLib.m file like import or adding path?

[Walter Roberson]

Like everything for MATLAB it would have to be on your MATLAB path, but you would not need to import

[Mohammad Askari]

Nice idea! The only downside is that it creates a false warning ("this function might be unused") for every individual sub-function. Do you have a workaround for this ?

[per isakson]

"false warning"

Add the line

%#ok<*DEFNU> 

to mylib.m

[Marcel]

Works fantastic and is elegant. Thanks!

[Image Analyst]

You could also comment out the function(s) with %{ and %}.

For example:

%{
function out = MyFunction(in)
out = 2 * in;
end
%}

Answer 3

[Image Analyst]

You can do that but velocityCalc() and distanceTraveled() would only be available/seen to functions within the same file. If they need to be used by other m-files, you'd have to have them in separate files, unless they were a class. I've done this so I know it works. If you had a class with those functions in it, then any file could call any of those functions as a static method of the class.

Answer 4

[John D'Errico]

If your goal is to use those function independently, then they need to be saved as separate m-files, NOT in one large file. While it would indeed be possible to do that in theory, you would need to learn a fair amount about function handles to do so. As well, you would need to call a main function, then having it return function handles for each sub-function that you might call in the future.

If you are somehow thinking of having an actual script that also has a mainline, but with functions defined within, that is not possible. Scripts cannot also contain function definitions, except for the case of function handles created in one line.

Simple save each function as an independent m-file.

[Image Analyst]

Starting with R2016b, you can have function(s) below a script all within the same m-file.