Round value ???

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nayomi
nayomi on 18 Oct 2011
Dear all,
I have to round a number to a specified number of decimal points.Anybody can help me??
Thank you

Accepted Answer

Daniel Shub
Daniel Shub on 18 Oct 2011

More Answers (2)

Walter Roberson
Walter Roberson on 18 Oct 2011
That cannot be done exactly in binary floating point arithmetic. Just the same way that you cannot exactly represent 1/3 in a fixed number of decimal digits, 1/100 cannot be exactly represented in binary digits.
It is possible to display something with two decimal places, such as by using
disp(sprintf('%.2f', 343.945584))
but you cannot store 343.95 exactly in a floating point number: try
sprintf('%.99f\n', 343.95)
and notice that it is not exactly 343.95 that is stored.
If you do not mind that you can only numerically get a close approximation, then use:
round(N*100)/100
  1 Comment
Image Analyst
Image Analyst on 18 Oct 2011
Walter, as you know this is a frequently asked question, since you've repeated it bazillions of times. Yet it's not in the FAQ (that I could find anyway). I'm thinking it should be added to section 6 on Math/Algorithms. What do you think? You can add it, or I could if you want.

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Pritesh Shah
Pritesh Shah on 18 Oct 2011
Also, Please see Cell, fix and round function for the same. If you want decimal point fix,
Also, You can you format function.
Thank you
  1 Comment
Walter Roberson
Walter Roberson on 18 Oct 2011
I think you mean ceil rather than cell.
The "format" function cannot be used to get a precise number of decimal places, except for "format bank"

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