I am having trouble with the menu and switch case command because every time I try to get an answer for pressure, I get 5 answers in a matrix instead of one. Does anyone know what I am doing wrong?

clear all, close all, nfig = 0;

choice = menu('Choose a gas.','Helium Gas','Hydrogen Gas','Oxygen Gas',...
    'Chlorine Gas','Carbon Dioxide Gas');

switch choice
    case 1
        a = 0.0341; b = 0.0237;
    case 2
        a = 0.244; b = 0.0266;
    case 3
        a = 1.36; b = 0.0318;
    case 4
        a = 6.49; b = 0.0562;
    case 5
        a = 3.59; b = 0.0427;
end

prompt = 'What is the temperature? (C) ';
T = input(prompt)+273;

prompt = 'What is the molar volume? (L/mol) ';
V = input(prompt);

Pressure = VDW(T,V);

prompt = Pressure;

Answer 1

[Sean de Wolski]

It must be whatever VDW is doing because running everything up to there gives scalar values.

Put a breakpoint in VDW and see what it's doing!

[Yianni]

My function for VDW is:

P = ((R*T)./(V-b))-(a/(V*V))

This is an equation for the van der Waals Equation.

[Sean de Wolski]

What's R?

[Yianni]

R = 0.08206;