Thread Subject: Precision

Can anyone suggest me how to set the precision of a give number in MATLAB, something like there is number say n=5.4356 which is calculated by a program. Now I would like to see the result upto say 2 places of decimal i.e.5.44. How can I do this in MATLAB?

Try sprintf('%.2f',n) . This will format and rount it to two places of decimal, but the value returned is a string.



"Sudipta Basu" <tupai_basu2004@yahoo.com> wrote in message <h03ue5$mni$1@fred.mathworks.com>...
> Can anyone suggest me how to set the precision of a give number in MATLAB, something like there is number say n=5.4356 which is calculated by a program. Now I would like to see the result upto say 2 places of decimal i.e.5.44. How can I do this in MATLAB?

"Sudipta Basu" <tupai_basu2004@yahoo.com> wrote in message <h03ue5$mni$1@fred.mathworks.com>...
> Can anyone suggest me how to set the precision of a give number in MATLAB, something like there is number say n=5.4356 which is calculated by a program. Now I would like to see the result upto say 2 places of decimal i.e.5.44. How can I do this in MATLAB?

% Because of floating point precision,
% you can't do this EXACTLY, but you can come close...

% For example:
round(100*n)/100
% will "sorta" round n to two decimal places.
% 5.1234 -> 5.12 may actualy be stored as 5.119999...

% Another option is something like:
str2num(num2str(n,2))
% to get n to 2 significant digits.
% Same floating point precision problem again.

% See Q6.1 of the MATLAB FAQ at:
http://matlabwiki.mathworks.com/MATLAB_FAQ

Hi Sudipta,

You can execute this in Matlab:

>> format bank
>> n=5.4356

n =

          5.44

Best wishes, Marcus
Tomlab Optimization Inc.
http://tomopt.com/
http://tomsym.com/

"Marcus M. Edvall" <edvall@gmail.com> wrote in message <e53d7a93-1b49-4b17-8906-9a19859bea93@h23g2000vbc.googlegroups.com>...
> Hi Sudipta,
>
> You can execute this in Matlab:
>
> >> format bank
> >> n=5.4356
>
> n =
>
> 5.44
>
> Best wishes, Marcus
> Tomlab Optimization Inc.
> http://tomopt.com/
> http://tomsym.com/

Thanx Marcus. Your suggestion has been quite helpful to me.

"Sudipta Basu" <tupai_basu2004@yahoo.com> wrote in message
news:h04qg9$6gn$1@fred.mathworks.com...
> "Marcus M. Edvall" <edvall@gmail.com> wrote in message
> <e53d7a93-1b49-4b17-8906-9a19859bea93@h23g2000vbc.googlegroups.com>...
>> Hi Sudipta,
>>
>> You can execute this in Matlab:
>>
>> >> format bank
>> >> n=5.4356
>>
>> n =
>>
>> 5.44
>>
>> Best wishes, Marcus
>> Tomlab Optimization Inc.
>> http://tomopt.com/
>> http://tomsym.com/
>
> Thanx Marcus. Your suggestion has been quite helpful to me.

Be careful. The code Marcus gave you simply changes how the number is
_displayed_. It has no effect on how the number is _stored_ -- any
calculations that you perform later on will still use the full value of n,
not just 5.44.

The approach "someone" described earlier in this thread rounds the value of
the number, not just how it's displayed, but as he or she says there are
some caveats of which you should be aware. I second his/her recommendation
to read question 6.1 in the newsgroup FAQ (and the documents linked at the
end of that answer.)

--
Steve Lord
slord@mathworks.com