Format a matrix with entries displayed as exact values

I am trying to print a matrix with its entries displayed as exact values not fractional approximations. For example, the following code should print A exactly as it is initialized (not approximate sqrt(2) as 1393/985) but displays fractions. What format specification instead of rat should be used?

format rat 
AB = [0 1 1; sqrt(2) 2 0; 0 1 1];
disp("AB: "); disp(AB) 

Answer 1

[Dana]

I'm not sure exactly what you're after. Here are some possibilities

>> format short
>> disp(AB)
         0    1.0000    1.0000
    1.4142    2.0000         0
         0    1.0000    1.0000

>> format long
>> disp(AB)
                   0   1.000000000000000   1.000000000000000
   1.414213562373095   2.000000000000000                   0
                   0   1.000000000000000   1.000000000000000

>> format shortg
>> disp(AB)
            0            1            1
       1.4142            2            0
            0            1            1
            
>> format longg
>> disp(AB)
                         0                         1                         1
           1.4142135623731                         2                         0
                         0                         1                         1

If you're saying you want it to literally say "sqrt(2)", then you can't do that using numeric arrays. As soon as you set an element of a numeric array equal to sqrt(2), MATLAB forgets how it arrived at that value, and only remembers the floating-point approximation. The only option I can see would be to use the Symbolic Toolbox:

>> AB = sym([0 1 1; sqrt(sym(2)) 2 0; 0 1 1]);
>> disp("AB: "); disp(AB) 
AB: 
[       0, 1, 1]
[ 2^(1/2), 2, 0]
[       0, 1, 1]

You can then convert this to a numeric array any time using eval:

>> eval(AB)
ans =
            0            1            1
       1.4142            2            0
            0            1            1

[Aleem Andrew]

Thank you for your answer

[madhan ravi]

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[Dana]

Not sure what the relevance of that is here madhan? This use of eval isn't about variable naming, it's about converting a symbolic array to a numeric one.

[madhan ravi]

a simple use of double() would do the trick. Generally eval() is not recommended, if you read that link entirely, it’ll tell you the reasons why not to use that function.