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round off in matlab

Asked by dav

dav (view profile)

on 5 Apr 2013


I am running a large simulation in matlab. I have noticed that matlab rounds off after 4 decimal places and this affects my results.

Is there a way to give a command at the beginning of the program so that matlab does the round off after about 10 decimal places?


1 Comment

Roger Stafford

Roger Stafford (view profile)

on 6 Apr 2013

Matlab's 'double' does not round off after four decimals as far as the actual computations are concerned. It is always accurate to about 16 significant decimal digits. It's only the display of its results that is given to four digits if you are using format short. It is important to understand the difference.

Try this experiment.

 format short
 x = pi^2
 fprintf('x = %19.16f\n',x)

The second display is accurate to 16 places which means that this was the accuracy of the original computation. The 'short' format only displayed four of the significant digits.


dav (view profile)


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1 Answer

Answer by Azzi Abdelmalek

Azzi Abdelmalek (view profile)

on 5 Apr 2013
Accepted answer
 format long



dav (view profile)

on 5 Apr 2013


should you put a ";" after this command?

And is there a way to specify the number of decimal places?

Azzi Abdelmalek

Azzi Abdelmalek (view profile)

on 5 Apr 2013
Azzi Abdelmalek

Azzi Abdelmalek (view profile)

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