I don't know why it keeps saying illegal use of "case"

% P2
function k = ThCond(T,alloyname)
%Input arguments:
%K is the temperature as an array
%The alloy name associated with the temperature array
%Outputs:
%k, the thermal conductivity as an array the same size as T

switch ThCond
    case {'Al1'}
        if 298<=T && T<=840
            k=149.7+0.0809*T-(1*10^-4)*T^2
        else
            ('Error in code')
    case {'Al2'}
        if 298<=T && T<=773
            k=76.64+0.2633*T-(2*10^-4)*T^2
        else
            Error('error in code')
    case {'Al3'}
        if 298<=T && T<=890
            k=124.7+0.56*T+(1*10^-5)*T^2
        else
            Error('error in code')
    case {'Cu1'}
        if 100<=T && T<=1200
            k=453.9-0.1054*T
        else
            Error('error in code')
    case {'Cu2'}
        if 460<=T && T<=1188
            k=140.62+(112.14*10^-4)*T
        else
            Error('error in code')
    case {'Cu3'}
        if T<=1443
            k=16.041+(438.9*10^-4)*T
        else
            Error('error in code')
    case {'St1'}
        if 400<=T && T<=1000
            k=76.63-0.0459*T
        else
            Error('error in code')
    case {'St2'}
        if 298<=T && T<=1573
            k=6.31+(27.2*10^-3)*T-(7.0*10^-6)*T^2
        else
            Error('error in code')
    case {'St3'}
        if T<=1727
            k=20+(61.5*10^-4)*T
        else
            Error('error in code')
        end
    end

Answer 1

[Stephen23]

It looks like Python code, because all of the if statements are missing the end (which is required by MATLAB):

if 298<=T && T<=840
    k=149.7+0.0809*T-(1*10^-4)*T^2
else
    ('Error in code')
end % <---- you are missing this everywhere!

This is a good example of why it is important to read the documentation for every function and operator, no matter how trivial it might seem.

Answer 2

[Star Strider]

If I understand what you want to do, using:

switch alloyname

would probably produce the desired behaviour.