Round with significant digits

Version 1.6.0.0 (3.05 KB) by François Beauducel
Rounds towards the nearest number with N significant digits.
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Updated 3 Apr 2015

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Editor's Note: This file was selected as MATLAB Central Pick of the Week

This little function rounds a number (or the elements of a vector ot matrix) towards the nearest number with N significant digits.
Examples:
roundsd(0.012345,3) returns 0.0123
roundsd(12345,2) returns 12000
roundsd(12.345,4,'ceil') returns 12.35
This is a useful complement to Matlab's ROUND, ROUND10 and ROUNDN (Mapping toolbox), especially when dealing with data with a large variety of order of magnitudes.

I was about to upload this file when I found "sd_round.m" by Edward Zechmann (see aknowledgment), which has similar feature (and more). But, because my script is very different in coding (much much shorter), I decided to share it anyway.

Cite As

François Beauducel (2026). Round with significant digits (https://uk.mathworks.com/matlabcentral/fileexchange/26212-round-with-significant-digits), MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R13
Compatible with any release
Platform Compatibility
Windows macOS Linux
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Acknowledgements

Inspired by: Round to a Specified Number of Significant Digits

Inspired: RADIOMICS

Version Published Release Notes
1.6.0.0

fix a problem with vectors with negative and positive exponent values (problem since the last update only).
1.5.0.0

solve the floating point arithmetic problem with roundsd(3.55,2) pointed out by Will and Yuri K.
1.3.0.0

- adds different methods for rounding;
- corrects a bug for 0 values (now produces 0 instead of NaN), thanks to Daniel Armyr's comment.
1.2.0.0

works with negative numbers.
1.1.0.0

works with negative numbers.
1.0.0.0