MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn moreOpportunities for recent engineering grads.

Apply Today
Asked by huda nawaf on 11 Jan 2012

hi, how convert fraction part into integer :

30.6789 to 6789

thanks

*No products are associated with this question.*

Answer by Jonathan Sullivan on 11 Jan 2012

Looks like you want to round to the nearest 0.001. You can do this with the following:

x = 30.6789 % Or whatever your data is base = 0.001; % Or whatever you are rounding too. x_rounded = round(x./base).*base;

Hope this helps!

huda nawaf on 11 Jan 2012

thanks,

but i need isolate the integer from fraction , then i can change the fraction as i need.

i need get the fraction part whatever it, i do not know it and do not know it's lengths.

i need the fraction part alone , then may hide in it bits then return it as fraction after modify it

Walter Roberson on 11 Jan 2012

The fraction you are looking for would have to be in base 10, but in base 10 it would be inappropriate to work at the *bit* level; instead you would have to work at the *dit* level (though the proper name for a "dit" is a "ban"; http://en.wikipedia.org/wiki/Ban_%28information%29)

Mixing base 10 and base 2 needs to be done very carefully!

Answer by Image Analyst on 11 Jan 2012

How about this:

a=30.6789; out = (a - floor(a)) * 10000

You do need the base, for example 10000. Why? Because the fraction never ends as I'm sure you know because you've read the FAQ. Want proof? Check this out:

format long; a % Display it. It won't be 30.6789!

>> a = 30.678899999999999

So that's why you have to pick some number of decimal places.

Walter Roberson on 11 Jan 2012

For the benefit of those who might not have read the referenced FAQ,

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

## 2 Comments

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/25860#comment_57227

i want add something

when i get 6789 for ex.

i want change it into 6790 for ex.

and return this no. into fraction such as: 30.6790

thanks

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/25860#comment_57228

Why not just add .0001 ?