How to show exact answers in MATLAB

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Suh-Shin
Suh-Shin 2013-9-24
编辑： Mr.Gh 2019-12-14
Hello everyone, I run into this exact answer problem with MATLAB pretty frequently. My problem is right now when I'm trying to do an inverse of a matrix containing square roots, it gives me answers in fractions or in decimals. I want it to show the square roots and other functions. How would I go about doing this? I've googled a while and all they say are precision values and rounding and what not, but nothing to do with these square roots.
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Mr.Gh
Mr.Gh 2019-12-14
编辑：Mr.Gh 2019-12-14
Use this code to see the exact answer:
>>A = inv([sqrt(sym(21))]);
>>answer = double(A)
answer = 2.1822e-01

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回答（3 个）

Mahdi
Mahdi 2013-9-24
Why don't you try an approach where you use square the matrix to find out what the numbers are?
For example
MatrixSquared=Matrix.^2;
Then you would be able to see which numbers were square rooted. I would also suggest placing
format rat
before the code.
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Suh-Shin
Suh-Shin 2013-9-24
Hey, I tried your approach, but it only gives me fractions. I want MATLAB to show me square roots and powers. I tried the following:
format rat;
inv([sqrt(21)]);
it shows me fractions, but I want to see square roots

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Matt J
Matt J 2013-9-24
编辑：Matt J 2013-9-24
Sounds like you're trying to do a symbolic matrix inverse operation. The Symbolic Math Toolbox will let you do that, see
http://www.mathworks.com/help/symbolic/inv.html
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Karan Gill
Karan Gill 2018-2-13
To add onto Walter's reply, this topic explains differences in arithmetic.

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Shashank Prasanna
Shashank Prasanna 2013-9-24
Use format to reset your display format or choose a different display format:
>> format
http://www.mathworks.com/help/matlab/ref/format.html

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