how to covert a log number into nature number?

I have an answer poped up like this below:

log(5^(1/2) + 2)/4 + 5^(1/2)/2

How can I convert it into a nature number?

Thanks

[jonas]

nature number? You want to express the results as a fraction?

[gao peter]

Hi Jonas,

yes, i would like to convert it into fractions. could you show me how to do it?

Thanks

Answer 1

[James Tursa]

I'm assuming this is the result of some symbolic manipulation? Try converting it to double:

result = double( your expression result );

E.g.,

>> log(sqrt(sym(5)) + 2)/4 + sqrt(sym(5))/2
ans =
log(5^(1/2) + 2)/4 + 5^(1/2)/2
>> double(ans)
ans =
    1.4789

Answer 2

[jonas]

You can get the approximate fractions using rat:

[num,den] = rat(log(5^(1/2) + 2)/4 + 5^(1/2)/2)

yields 1791/1211 which is about 1.47894

You can also specify a tolerance, if you accept a larger error

[up,down] = rat(log(5^(1/2) + 2)/4 + 5^(1/2)/2,0.1)

gives 3/2