Undefined function or variable in MATLAB

I have this function saved as element.m Whenever I call on it I say element(Hydrogen) I am trying to get it to display the name, symbol, atomic number, category, ... But it keeps saying Undefined function or variable 'Hydrogen' I don't understand why its doing this.

function [Name, Symbol, Atomic_Number, Category, Proton, Neutron, Electron]=element(e)

%Inputs:
%e - 'Hydrogen' ;
%Outputs:
%Name
%Symbol
%Atomic_Number
%Category
%Proton
%Neutron
%Electron
e=[Hydrogen Helium]

if e=='Hydrogen'
  Name='Hydrogen';
  Symbol='H';
  Atomic_Number='1';
  Category='Nonmetal';
  Proton='1';
  Neutron='';
  Electron='1';
elseif e==Helium
  Name='Helium'
  Symbol='H'
  Atomic_Number='1'
  Category='Noble Gas'
  Proton='4'
  Neutron='2'
  Electron='4'

end 

end

Answer 1

[per isakson]

What is e=[Hydrogen Helium] intended to do?

[Joshua]

I meant to delete e=[Hydrogen Helium]

[per isakson]

???

At that point in the code neither Hydrogen nor Helium exists.

[A,B] concatenates the variables A and B

[Joshua]

how would i define hydrogen and helium if i wanted to get the name, category, symbol ...

[per isakson]

Remove the line

    e=[Hydrogen Helium]

and replace

    e=='Hydrogen'

by

    strcmp( e, 'Hydrogen' )

or

    all( e=='Hydrogen' )

Then try to run the function

[per isakson]

Have a look at these links on debugging in Matlab

• Debugging in MATLAB
• Debugging session
• Debugging Approaches

[Joshua]

I did what you said with both strcmp and all, i tried both of them, when i wrote element('Hydrogen') in the command window it said ans=Hydrogen, but i dont understand why its not giving me the other information as well.

[per isakson]

You have to make a call like

[Name,Symbol,Atomic_Number,Category,Proton,Neutron,Electron]=element('Hydrogen')

[Joshua]

Thanks it worked.

Answer 2

[Azzi Abdelmalek]

The variable Hydrogene is not defined in your code, how Matlab will recognize it?

[Joshua]

I am kind of new to MATLAB, how exactly would i define it if I wanted it to give me the Name, Category, Symbol ...

[Joshua]

Thanks it worked.

Answer 3

[Jason Schneider]

Remove

e = [Hydrogen Helium]

Use

strcmp as previously suggested.

Make sure when you call the function it is of the form:

[a b c d e f g] = element('Hydrogen')

You need to define where the rest of the output arguments will be assigned since they are internal variables to the function.

It seems this was also mentioned but the input argument needs to be a string or else Matlab will look for a variable that doesn't exist.

[Joshua]

Thanks it worked.