Help with cell if statement

Trying to make this code work

if Gas_driven(n) == {'Air'}
R = 286.9;
elseif Gas_driven(n) == 'Argon'
    R = 208;   
else 
    'Gas Constant not defined'
end

but it keeps coming up with this error

Undefined function or variable 'Air'.

Error in ExpansionShots (line 40)
if Gas_driven(n) == {Air}

[Stephen23]

The error message indicates that you are actually calling this ( Air is a variable/function):

if Gas_driven(n) == {Air}

but your code shows that you think that you are calling this ( 'Air' is a string):

if Gas_driven(n) == {'Air'}

Also note that == does not check if two strings are the same: you need to use strcmp or strcmpi, exactly as per Ilham Hardy's answer.

Answer 1

[Ilham Hardy]

Perhaps something like this?

if strcmpi(Gas_driven{n},'Air') == 1
      R = 286.9; 
elseif strcmpi(Gas_driven{n},'Argon') == 1
      R = 208; 
else 
      R = 'Gas Constant not defined';
end