MATLAB: Matrix dimensions must agree

MATLABprogramming

Hi,
i try to write this little program to have a simplified analysis for the mass of pressurizing Gas in two case: isothermal and isentropic. I used many prompt to insert the inputs and, as shown down, an if cicle. However it works just when i write 'isotermico' as input for the prompt4. If i write 'isoentropico' occurs and error:
Matrix dimensions must agree.
Error in
analisi_semplificata_massa_gas_pressurizzante
(line 52)
if Caso == 'isotermico'
I understand that the problem is the differnt length of the words 'isotermico' and 'isoentropico', in fact if i write 'isoentropi' it works, but i'd like to know how to write it correctly without this ignorant ploy.
prompt4 = 'Caso: '; % INSERIRE CASO (Es.: isotermico, isoentropico);
Caso = input(prompt4,'s');
prompt5 = 'Inserire pressione serbatoio gas: '
P_0 = input(prompt5)
prompt6 = 'Inserire pressione finale del propellente nel serbatoio: '
P_p = input(prompt6)
prompt7 = 'Inserire valore della temperatura nel serbatoio: '
T_0 = input(prompt7);
if Caso == 'isotermico'
    
    V_0 = (V_p*P_p)/(P_0-P_p)
    
elseif Caso == 'isoentropico'
    
    prompt8 = 'Inserire valore di k: '
    k = input(prompt8);
    V_0 = V_p/(((P_0/P_p)^(1/k))-1)
    
else
    display('Inserire funzione nello script')
end
   
m_0 = P_0*V_0/(R*T_0)
Summing:
I need to know how to write correctly the condition of the if cicle without any errors occurring due to the different length of the two text array 'isotermico' and 'isoentropic'.

Best Answer

Use strcmp for example
if strcmp(Caso,'isotermico')
A switch case expression can also be used nicely for this
switch Caso
    case 'isotermico'
         V_0 = (V_p*P_p)/(P_0-P_p)
    case 'isentropico'
            prompt8 = 'Inserire valore di k: '
            k = input(prompt8);
            V_0 = V_p/(((P_0/P_p)^(1/k))-1)
    
    otherwise
    display('Inserire funzione nello script')
end
        
end
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