# How to display error using error function?

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Porgs on 1 May 2018
Commented: Walter Roberson on 12 Aug 2019
I have a program that computes thermal conductivity based on an input of a certain alloy and temperature. I would like to have the function display an error if the wrong alloy is inputted. Would It be possible to do this with the error function? This is the code I have so far.
function k = ThCond(alloy,T) % T = input temperature
k = zeros(1,numel(T));
for a = 1:numel(T)
if (298 <= T(a)) && (T(a) <= 840) && strcmp(alloy,'Al2')
k(a) = 149.7 + 0.0809.*T(a) - (1.*10^(-4)).*(T(a).^2);
elseif (298 <= T(a)) && (T(a) <= 773)
k(a) = 76.64 + 0.2633.*T(a) - (2.*10^(-4)).*(T(a)^2);
end
if (293 <= T(a)) && (T(a) <= 890) && strcmp(alloy,'Al3')
k(a) = 124.7 + 0.56.*T(a) + (1*10^(-5)).*(T(a)^2);
end
if (100 <= T(a)) && (T(a) <= 1200) && strcmp(alloy,'Cu1')
k(a) = 453.9 - 0.1054.*T(a);
end
if (460 <= T(a)) && (T(a) <= 1188) && strcmp(alloy,'Cu2')
k(a) = 140.62 + (112.14.*10^(-4)).*T(a);
end
if T(a) <= 1443 && strcmp(alloy,'Cu3')
k(a) = 16.041 + (438.9.*10^(-4)).*T(a);
end
if (400 <= T(a)) && (T(a) <= 1000) && strcmp(alloy,'St1')
k(a) = 76.63 - 0.0459.*T(a);
end
if (298 < T(a)) && (T(a) < 1573) && strcmp(alloy,'St2')
k(a) = 6.31 + ((27.2.*10^(-3)).*T(a)) - (7.*10^(-6)).*(T(a).^2);
end
if T(a) <= 1727 && strcmp(alloy,'St3')
k(a) = 20 + (61.5.*10^(-4)).*T(a);
end
end
end
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Porgs on 1 May 2018
Not really, I would like to use the error fuction to display a personal error message that I write, to the user.
Walter Roberson on 1 May 2018
error('Alloy must be H2SO4 or CuTi2C6H8') ;

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### Accepted Answer

Wick on 1 May 2018
Simple enough then.
err = 'This is an error message.'; % perhaps something a bit more descriptive
error(err);
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### More Answers (3)

Porgs on 1 May 2018
Where would I put that in my code because I'm getting an error message when I'm trying to use this.
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Wick on 1 May 2018
That's literally what the 'error' function does. It displays an error and breaks execution (unless it's part of a try,catch structure). So you'd put it as the result of an 'else' statement or possibly as result of an 'otherwise' option in a switch,case structure.
If you you don't want an actual error message and just want text displayed to the screen you can use the 'disp' or 'warning' commands instead.

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Porgs on 1 May 2018
Ok thanks
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usha shree on 9 Aug 2019
one dimesional error with two elements
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Walter Roberson on 12 Aug 2019
Could you expand upon that remark?

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