error in large integers

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Eigo Takkeda
Eigo Takkeda 2012-3-21
I am currently working with fractions involving 10digit integers.
for example, typing 1168347147/863334886 into MATLAB produces the answer 4045/2989.
But I want to store the fractions exactly. How do I go about doing this?
Many thanks.

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回答（2 个）

Aldin
Aldin 2012-3-21
Hi,
use vpa functon
for example:
vpa('4045/2989',100) ---> for hundred digits
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Aldin
Aldin 2012-3-22
I think is more better to use smaller number like 4045/2989 ???
Aldin
Aldin 2012-3-22
Do you know:
1168347147/863334886 = 4045/2989

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Walter Roberson
Walter Roberson 2012-3-22
If you have the symbolic math toolbox, then
sym('1168347147/863334886')
Note that the result will be a symbolic number, not a double precision number.
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Walter Roberson
Walter Roberson 2012-3-22
Yes, if you do have the symbolic toolbox then you would be able to use symbolic numbers in further calculations; the results would be symbolic numbers.
There might be places along the way where you needed to convert the symbolic numbers to double precision using double(), as there are MATLAB routines that cannot work with symbolic numbers.
Aldin
Aldin 2012-3-22
Hello sir Walter,
Can you please explain:
>> sym('1168347147/863334886')
ans =
1168347147/863334886
>> ans * 1,4
ans =
8178430029/4316674430
--------------------------
But if i check last result with 'vpa' function i got this:
>> vpa('863334886*1,4)
ans = 1208668840.4

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