I want to throw the error that comes with entering a non number in a numeric only input

n = input('Please enter a number:\n');

I get this error and I want to throw it and write another error:

Error using input

Unrecognized function or variable 'k'.

Error in eer (line 1)

n = input('Please enter your name:\n');

Answer 1

[Wan Ji]

n = str2num(input('Please enter a number:\n','s'));
if(isempty(n))
error('You are entering a non number in a numeric only input')
end

[Nam Vinh Nguyen]

I apologize for I was not clear. I cannot use input('....' , 's') it has to be input()

[Wan Ji]

matlab input is a built-in function and the inner message cannot be changed as willing.

I donot know which version of matlab does not permit the usage of input function like input('....' , 's').

If you cannot use input('...','s'), then update you matlab to the newest version.

[Nam Vinh Nguyen]

Oh I can use input('..','s') but I need it to be numerical for mathematical reasons.

[Wan Ji]

So you tell the function that I can not achieve for mathematical reasons

[Nam Vinh Nguyen]

Sorry I am quite new to this, I just figured out that it does work, but the problem arise is that I cannot check if the user did not type anything and matlab keep asking me to use str2double( which doesn't work).

[Wan Ji]

str2num is ok, and it can also transfer string to double array. while str2double can not do that

[Wan Ji]

n = str2num(input('Please enter a number:\n','s'));
if(isempty(n))
error('You are entering a non number in a numeric only input')
end
n

the running resluts:

Case one （one number）:

Please enter a number:
100.0

n =

   100

Case two (multiple numbers)：

Please enter a number:
1,2,3

n =

     1     2     3
     

Case three (non-numeric input):

Please enter a number:
1.1.1.12
You are entering a non number in a numeric only input

So, for those non-numeric inputs, errors occur and a message is thrown to the command window.

[Nam Vinh Nguyen]

Yes but how can I tell the difference between when the user type nothing and when they type a non numeric letter?

[Wan Ji]

n = input('Please enter a number:\n','s');
if(isempty(n))
    error('You are entering nothing')
elseif(isempty(str2num(n)))
    error('You are entering a non number in a numeric only input')
end
n = str2num(n);

[Nam Vinh Nguyen]

Thank you so much king. It works !!